Herbicidal Isoxazolo[5,4-B]pyridines

ABSTRACT

The invention relates to isoxazolo[5,4-b]pyridine compounds of formula I, 
     
       
         
         
             
             
         
       
     
     to the agriculturally useful salts of isoxazolo[5,4-b]pyridine compounds of formula I, and to their use as herbicides.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.13/811,095, filed Jan. 18, 2013. U.S. application Ser. No. 13/811,095 isa National Stage application of International Application No.PCT/EP2011/062454, filed Jul. 20, 2011, which claims the benefit of U.S.Provisional Application No. 61/366,535, filed Jul. 22, 2010, the entirecontents of which are hereby incorporated herein by reference. Thisapplication also claims priority under 35 U.S.C. §119 to European PatentApplication No. 10170416.1, filed Jul. 22, 2010, the entire contents ofwhich is hereby incorporated herein by reference.

The present invention relates to isoxazolo[5,4-b]pyridines of generalformula I as defined below and to their use as herbicides. Moreover, theinvention relates to compositions for crop protection and to a methodfor controlling unwanted vegetation.

Compounds having an isoxazolo[5,4-b]pyridine moiety are known in theart. US2009163545 describes such compounds as lifespan-altering foreukaryotic organisms. According to WO2009015208, particular ureaderivatives show an antibacterial effect. Potential routes for synthesisof isoxazolo[5,4-b]pyridine compounds are known from Elbannany et al,Pharmazie (1988) 43(2), 128-129 and Volochnyuk et al, Journal ofCombinatorial Chemistry (2010) 12(4), 510-517.

In agriculture, there is a constant demand to develop novel activeingredients, which complement or outperform present methods of treatmentregarding activity, selectivity and environmental safety.

It is therefore an object of the present invention to provide chemicalcompounds, which are suitable as herbicides. In particular, it is anobject to identify chemical compounds with high herbicidal activity,preferably at low application rates, while leaving desirable plants,e.g. crop plants, unharmed.

These and further objects are achieved by isoxazolo[5,4-b]pyridines offormula I as defined below and by their agriculturally useful salts.

Accordingly, the present invention provides isoxazolo[5,4-b]pyridines offormula I

-   -   where in formula I, the variables are as defined below:    -   R¹ hydrogen, halogen, hydroxyl, C₁-C₆-alkyl, C₁-C₆-haloalkyl,        C₁-C₆-alkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,        C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl,        C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, phenyl, phenyl-C₁-C₄-alkyl;    -   R² hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,        C₁-C₆-alkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,        C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,        phenyl-C₁-C₄-alkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₆-alkoxy,        C₁-C₆-haloalkoxy, C₁-C₆-alkylthio, amino, C₁-C₆-alkylamino,        N,N-di-(C₁-C₆)-alkylamino, heterocyclyl; wherein the        heterocyclyl moieties of R² can be unsubstituted or substituted        with one or more radicals selected from halogen, nitro,        C₁-C₄-alkyl, C₁-C₄-haloalkyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,        C₁-C₄-alkoxycarbonyl, heterocyclyl, phenyl;        -   or R¹ and R² together form an C₃-C₅-alkanediyl;    -   R³ hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,        C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,        C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,        C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,        C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,        C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,        heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,        C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy,        C₁-C₆-haloalkoxy, C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino,        C₁-C₆-alkylamino, N,N-di-(C₁-C₆)-alkylamino, heterocyclyl,        phenyl; wherein the heterocyclyl and phenyl moieties of R³ can        be unsubstituted or substituted with one or more radicals        selected from halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl,        C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,        C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,        C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl,        C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl,        phenyl;    -   X OR⁴, SR⁵; NR⁶R⁷;    -   R⁴, R⁵ hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl,        C₁-C₆-hydroxyalkyl, C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,        C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl,        C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₂-C₆-alkenyloxy-C₁-C₆-alkyl,        C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,        C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,        C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,        N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,        [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),        N—(C₁-C₆-alkyl)]-aminocarbonyl-C₁-C₆-alkyl,        C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,        C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,        C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,        phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,        phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,        phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties        of R⁴ and R⁵ can be unsubstituted or substituted with one or        more radicals selected from halogen, C₁-C₄-alkyl,        C₁-C₄-haloalkyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,        C₁-C₄-alkoxycarbonyl, heterocyclyl, phenyl;    -   R⁶, R⁷ hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₂-C₆-alkenyl,        C₂-C₆-alkynyl, C₁-C₆-alkoxy, phenyl-C₁-C₆-alkoxy, phenyl, phenyl        substituted with halogen, C₃-C₆-cycloalkyl,        C₃-C₆-halocycloalkyl, SO₂R⁸;    -   R⁸ C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl,        C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, phenyl; wherein the        phenyl moiety of R⁸ can be unsubstituted or substituted with one        or more radicals selected from halogen, C₁-C₄-alkoxy,        C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl, phenyl;    -   and their agriculturally useful salts;

In addition, subject matter of the present invention is the use ofisoxazolo[5,4-b]pyridines of formula I as herbicides, i.e. their use forcontrolling harmful plants.

The present invention also provides compositions comprising at least oneisoxazolo[5,4-b]pyridine of formula I and auxiliaries customary forformulating crop protection agents.

The present invention furthermore provides a method for controllingunwanted vegetation, where a herbicidal effective amount of at least oneisoxazolo[5,4-b]pyridine of formula I is allowed to act on plants, theirseeds and/or their habitat. Application can be done before, duringand/or after, preferably during and/or after, the emergence of theundesirable plants.

Moreover, the invention relates to processes for preparingisoxazolo[5,4-b]pyridines of formula I.

Further embodiments of the present invention are evident from theclaims, the description and the examples. It is to be understood thatthe features mentioned above and still to be illustrated below of thesubject matter of the invention can be applied not only in thecombination given in each particular case but also in othercombinations, without leaving the scope of the invention.

As used herein, the terms “controlling” and “combating” are synonyms.

As used herein, the terms “undesirable vegetation”, “weeds” and “harmfulplants” are synonyms.

If the isoxazolo[5,4-b]pyridines of formula I as described herein arecapable of forming geometrical isomers, for example E/Z isomers, it ispossible to use both, the pure isomers and mixtures thereof, in thecompositions according to the invention.

If the isoxazolo[5,4-b]pyridines of formula I as described herein haveone or more centers of chirality and, as a consequence, are present asenantiomers or diastereomers, it is possible to use both, the pureenantiomers and diastereomers and their mixtures, in the compositionsaccording to the invention.

The terms used for organic groups in the definition of the variablesare, for example the expression “alkyl”, collective terms whichrepresent the individual members of these groups of organic units.

The prefix C_(x)-C_(y) denotes the number of possible carbon atoms inthe particular case.

halogen: fluorine, chlorine, bromine or iodine, especially fluorine,chlorine or bromine;alkyl and the alkyl moieties of composite groups such as alkoxy,alkylamino, alkylthio, alkoxycarbonyl: saturated straight-chain orbranched hydrocarbon radicals having 1 to 10 carbon atoms, preferablyC₁-C₆-alkyl or C₁-C₄-alkyl, such as methyl, ethyl, propyl,1-methylethyl, butyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl,pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl,1-ethylpropyl, hexyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl,1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4-methylpentyl,1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl,2,2-dimethylbutyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl,2-ethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl,1-ethyl-1-methylpropyl and 1-ethyl-2-methylpropyl; heptyl, octyl,2-ethylhexyl and positional isomers thereof; nonyl, decyl and positionalisomers thereof;haloalkyl: straight-chain or branched alkyl groups having 1 to 10 carbonatoms (as mentioned above), preferably C₁-C₆-haloalkyl orC₁-C₄-haloalkyl, where some or all of the hydrogen atoms in these groupsare replaced by halogen atoms as mentioned above. In one embodiment, thealkyl groups are substituted at least once or completely by a particularhalogen atom, preferably fluorine, chlorine or bromine. In a furtherembodiment, the alkyl groups are partially or fully halogenated bydifferent halogen atoms; in the case of mixed halogen substitutions, thecombination of chlorine and fluorine is preferred. Particular preferenceis given to (C₁-C₃)-haloalkyl, more preferably (C₁-C₂)-haloalkyl, suchas chloromethyl, bromomethyl, dichloromethyl, trichloromethyl,fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl,dichlorofluoromethyl, chlorodifluoromethyl, 1-chloroethyl, 1-bromoethyl,1-fluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, 2,2,2-trifluoroethyl,2-chloro-2-fluoroethyl, 2-chloro-2,2-difluoroethyl,2,2-dichloro-2-fluoroethyl, 2,2,2-trichloroethyl, pentafluoroethyl or1,1,1-trifluoroprop-2-yl;alkenyl and also the alkenyl moieties in composite groups, such asalkenyloxy: unsaturated straight-chain or branched hydrocarbon radicalshaving 2 to 10 carbon atoms and one double bond in any position.According to the invention, it may be preferred to use small alkenylgroups, such as (C₂-C₆)-alkenyl; on the other hand, it may also bepreferred to employ larger alkenyl groups, such as (C₅-C₈)-alkenyl.Examples of C₂-C₆-alkenyl groups are: ethenyl, 1-propenyl, 2-propenyl,1-methylethenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-methyl-1-propenyl,2-methyl-1-propenyl, 1-methyl-2-propenyl, 2-methyl-2-propenyl,1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl, 1-methyl-1-butenyl,2-methyl-1-butenyl, 3-methyl-1-butenyl, 1-methyl-2-butenyl,2-methyl-2-butenyl, 3-methyl-2-butenyl, 1-methyl-3-butenyl,2-methyl-3-butenyl, 3-methyl-3-butenyl, 1,1-dimethyl-2-propenyl,1,2-dimethyl-1-propenyl, 1,2-dimethyl-2-propenyl, 1-ethyl-1-propenyl,1-ethyl-2-propenyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl,5-hexenyl, 1-methyl-1-pentenyl, 2-methyl-1-pentenyl,3-methyl-1-pentenyl, 4-methyl-1-pentenyl, 1-methyl-2-pentenyl,2-methyl-2-pentenyl, 3-methyl-2-pentenyl, 4-methyl-2-pentenyl,1-methyl-3-pentenyl, 2-methyl-3-pentenyl, 3-methyl-3-pentenyl,4-methyl-3-pentenyl, 1-methyl-4-pentenyl, 2-methyl-4-pentenyl,3-methyl-4-pentenyl, 4-methyl-4-pentenyl, 1,1-dimethyl-2-butenyl,1,1-dimethyl-3-butenyl, 1,2-dimethyl-1-butenyl, 1,2-dimethyl-2-butenyl,1,2-dimethyl-3-butenyl, 1,3-dimethyl-1-butenyl, 1,3-dimethyl-2-butenyl,1,3-dimethyl-3-butenyl, 2,2-dimethyl-3-butenyl, 2,3-dimethyl-1-butenyl,2,3-dimethyl-2-butenyl, 2,3-dimethyl-3-butenyl, 3,3-dimethyl-1-butenyl,3,3-dimethyl-2-butenyl, 1-ethyl-1-butenyl, 1-ethyl-2-butenyl,1-ethyl-3-butenyl, 2-ethyl-1-butenyl, 2-ethyl-2-butenyl,2-ethyl-3-butenyl, 1,1,2-trimethyl-2-propenyl,1-ethyl-1-methyl-2-propenyl, 1-ethyl-2-methyl-1-propenyl and1-ethyl-2-methyl-2-propenyl;alkynyl and the alkynyl moieties in composite groups: straight-chain orbranched hydrocarbon groups having 2 to 10 carbon atoms and one or twotriple bonds in any position, for example C₂-C₆-alkynyl, such asethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 3-butynyl,1-methyl-2-propynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 4-pentynyl,1-methyl-2-butynyl, 1-methyl-3-butynyl, 2-methyl-3-butynyl,3-methyl-1-butynyl, 1,1-dimethyl-2-propynyl, 1-ethyl-2-propynyl,1-hexynyl, 2-hexynyl, 3-hexynyl, 4-hexynyl, 5-hexynyl,1-methyl-2-pentynyl, 1-methyl-3-pentynyl, 1-methyl-4-pentynyl,2-methyl-3-pentynyl, 2-methyl-4-pentynyl, 3-methyl-1-pentynyl,3-methyl-4-pentynyl, 4-methyl-1-pentynyl, 4-methyl-2-pentynyl,1,1-dimethyl-2-butynyl, 1,1-dimethyl-3-butynyl, 1,2-dimethyl-3-butynyl,2,2-dimethyl-3-butynyl, 3,3-dimethyl-1-butynyl, 1-ethyl-2-butynyl,1-ethyl-3-butynyl, 2-ethyl-3-butynyl and 1-ethyl-1-methyl-2-propynyl;cycloalkyl and also the cycloalkyl moieties in composite groups: mono-or bicyclic saturated hydrocarbon groups having 3 to 10, in particular 3to 6, carbon ring members. Examples for C₃-C₆-cycloalkyl are:cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl orcyclooctyl. Examples of bicyclic radicals comprise bicyclo[2.2.1]heptyl,bicyclo[3.1.1]heptyl, bicyclo[2.2.2]octyl and bicyclo[3.2.1]octyl;halocycloalkyl and the halocycloalkyl moieties in composite groups:monocyclic saturated hydrocarbon groups having 3 to 10 carbon ringmembers (as mentioned above) in which some or all of the hydrogen atomsmay be replaced by halogen atoms as mentioned above, in particularfluorine, chlorine and bromine;cycloalkenyl: monocyclic monounsaturated hydrocarbon groups having 3 to10, 3 to 8, 3 to 6, preferably 5 to 6, carbon ring members, such ascyclopenten-1-yl, cyclopenten-3-yl, cyclohexen-1-yl, cyclohexen-3-yl,cyclohexen-4-yl and the like;alkoxy: an alkyl group as defined above, which is attached via anoxygen, preferably having 1 to 10, more preferably 1 to 6 or 1 to 4carbon atoms. Examples are: methoxy, ethoxy, n-propoxy, 1-methylethoxy,butoxy, 1-methylpropoxy, 2-methylpropoxy or 1,1-dimethylethoxy, and alsofor example, pentoxy, 1-methylbutoxy, 2-methylbutoxy, 3-methylbutoxy,1,1-dimethylpropoxy, 1,2-dimethylpropoxy, 2,2-dimethylpropoxy,1-ethylpropoxy, hexoxy, 1-methylpentoxy, 2-methylpentoxy,3-methylpentoxy, 4-methylpentoxy, 1,1-dimethylbutoxy,1,2-dimethylbutoxy, 1,3-dimethylbutoxy, 2,2-dimethylbutoxy,2,3-dimethylbutoxy, 3,3-dimethylbutoxy, 1-ethylbutoxy, 2-ethylbutoxy,1,1,2-trimethylpropoxy, 1,2,2-trimethylpropoxy, 1-ethyl-1-methylpropoxyor 1-ethyl-2-methylpropoxy;haloalkoxy: alkoxy as defined above, where some or all of the hydrogenatoms in these groups are replaced by halogen atoms as described aboveunder haloalkyl, in particular by fluorine, chlorine or bromine.Examples are OCH₂F, OCHF₂, OCF₃, OCH₂Cl, OCHCl₂, OCCl₃,chlorofluoromethoxy, dichlorofluoromethoxy, chlorodifluoromethoxy,2-fluoroethoxy, 2-chloroethoxy, 2-bromoethoxy, 2-iodoethoxy,2,2-difluoroethoxy, 2,2,2-trifluoroethoxy, 2-chloro-2-fluoroethoxy,2-chloro-2,2-difluoroethoxy, 2,2-dichloro-2-fluoroethoxy,2,2,2-trichloroethoxy, OC₂F₅, 2-fluoropropoxy, 3-fluoropropoxy,2,2-difluoropropoxy, 2,3-difluoropropoxy, 2-chloropropoxy,3-chloropropoxy, 2,3-dichloropropoxy, 2-bromopropoxy, 3-bromopropoxy,3,3,3-trifluoropropoxy, 3,3,3-trichloropropoxy, OCH₂—C₂F₅, OCF₂—C₂F₅,1-(CH₂F)-2-fluoroethoxy, 1-(CH₂Cl)-2-chloroethoxy,1-(CH₂Br)-2-bromoethoxy, 4-fluorobutoxy, 4-chlorobutoxy, 4-bromobutoxyor nonafluorobutoxy; and also 5-fluoropentoxy, 5-chloropentoxy,5-bromopentoxy, 5-iodopentoxy, undecafluoropentoxy, 6-fluorohexoxy,6-chlorohexoxy, 6-bromohexoxy, 6-iodohexoxy or dodecafluorohexoxy;aryl: 6 to 10-membered, aromatic carbocycle with 6, 7, 8, 9 or 10 carbonatoms. Examples of preferred aryl are phenyl or naphthyl;heterocycle: 5-, 6-, 7-, 8-, 9- or 10-membered saturated, partiallyunsaturated or aromatic monocyclic ring or bicyclic ring system, whichcontains 1, 2, 3 or 4 heteroatoms from the group consisting of O, N andS as ring members, and may furthermore contain one or two CO, SO, SO₂groups as ring members, where the heterocycle in question may beattached via a carbon atom or, if present, via a nitrogen atom. Inparticular:

-   -   a three, five- or six-membered saturated or partially        unsaturated heterocycle which comprises one, two, three or four        heteroatoms from the group consisting of O, N and S as ring        members: for example monocyclic saturated or partially        unsaturated heterocycles which, in addition to carbon ring        members, comprise one, two or three nitrogen atoms and/or one        oxygen or sulfur atom or one or two oxygen and/or sulfur atoms,        for example aziridine, oxirane, 2-tetrahydrofuranyl,        3-tetrahydrofuranyl, 2-tetrahydrothienyl, 3-tetrahydrothienyl,        2-pyrrolidinyl, 3-pyrrolidinyl, 3-isoxazolidinyl,        4-isoxazolidinyl, 5-isoxazolidinyl, 3-isothiazolidinyl,        4-isothiazolidinyl, 5-isothiazolidinyl, 3-pyrazolidinyl,        4-pyrazolidinyl, 5-pyrazolidinyl, 2-oxazolidinyl,        4-oxazolidinyl, 5-oxazolidinyl, 2-thiazolidinyl,        4-thiazolidinyl, 5-thiazolidinyl, 2-imidazolidinyl,        4-imidazolidinyl, 1,2,4-oxadiazolidin-3-yl,        1,2,4-oxadiazolidin-5-yl, 1,2,4-thiadiazolidin-3-yl,        1,2,4-thiadiazolidin-5-yl, 1,2,4-triazolidin-3-yl,        1,3,4-oxadiazolidin-2-yl, 1,3,4-thiadiazolidin-2-yl,        1,3,4-triazolidin-2-yl, 2,3-dihydrofur-2-yl,        2,3-dihydrofur-3-yl, 2,4-dihydrofur-2-yl, 2,4-dihydrofur-3-yl,        2,3-dihydrothien-2-yl, 2,3-dihydrothien-3-yl,        2,4-dihydrothien-2-yl, 2,4-dihydrothien-3-yl, 2-pyrrolin-2-yl,        2-pyrrolin-3-yl, 3-pyrrolin-2-yl, 3-pyrrolin-3-yl,        2-isoxazolin-3-yl, 3-isoxazolin-3-yl, 4-isoxazolin-3-yl,        2-isoxazolin-4-yl, 3-isoxazolin-4-yl, 4-isoxazolin-4-yl,        2-isoxazolin-5-yl, 3-isoxazolin-5-yl, 4-isoxazolin-5-yl,        2-isothiazolin-3-yl, 3-isothiazolin-3-yl, 4-isothiazolin-3-yl,        2-isothiazolin-4-yl, 3-isothiazolin-4-yl, 4-isothiazolin-4-yl,        2-isothiazolin-5-yl, 3-isothiazolin-5-yl, 4-isothiazolin-5-yl,        2,3-dihydropyrazol-1-yl, 2,3-dihydropyrazol-2-yl,        2,3-dihydropyrazol-3-yl, 2,3-dihydropyrazol-4-yl,        2,3-dihydropyrazol-5-yl, 3,4-dihydropyrazol-1-yl,        3,4-dihydropyrazol-3-yl, 3,4-dihydropyrazol-4-yl,        3,4-dihydropyrazol-5-yl, 4,5-dihydropyrazol-1-yl,        4,5-dihydropyrazol-3-yl, 4,5-dihydropyrazol-4-yl,        4,5-dihydropyrazol-5-yl, 2,3-dihydrooxazol-2-yl,        2,3-dihydrooxazol-3-yl, 2,3-dihydrooxazol-4-yl,        2,3-dihydrooxazol-5-yl, 3,4-dihydrooxazol-2-yl,        3,4-dihydrooxazol-3-yl, 3,4-dihydrooxazol-4-yl,        3,4-dihydrooxazol-5-yl, 3,4-dihydrooxazol-2-yl,        3,4-dihydrooxazol-3-yl, 3,4-dihydrooxazol-4-yl, 2-piperidinyl,        3-piperidinyl, 4-piperidinyl, 2-tetrahydropyranyl,        4-tetrahydropyranyl, 2-tetrahydrothienyl,        3-hexahydropyridazinyl, 4-hexahydropyridazinyl,        2-hexahydropyrimidinyl, 4-hexahydropyrimidinyl,        5-hexahydropyrimidinyl, 2-piperazinyl,        1,3,5-hexahydrotriazin-2-yl and 1,2,4-hexahydrotriazin-3-yl and        also the corresponding -ylidene radicals;    -   a seven-membered saturated or partially unsaturated heterocycle        which comprises one, two, three or four heteroatoms from the        group consisting of O, N and S as ring members: for example        mono- and bicyclic heterocycles having 7 ring members which, in        addition to carbon ring members, comprise one, two or three        nitrogen atoms and/or one oxygen or sulfur atom or one or two        oxygen and/or sulfur atoms, for example tetra- and        hexahydroazepinyl, such as 2,3,4,5-tetrahydro[1H]azepin-1-, -2-,        -3-, -4-, -5-, -6- or -7-yl, 3,4,5,6-tetrahydro[2H]azepin-2-,        -3-, -4-, -5-, -6- or -7-yl, 2,3,4,7-tetrahydro[1H]azepin-1-,        -2-, -3-, -4-, -5-, -6- or -7-yl,        2,3,6,7-tetrahydro[1H]azepin-1-, -2-, -3-, -4-, -5-, -6- or        -7-yl, hexahydroazepin-1-, -2-, -3- or -4-yl, tetra- and        hexahydrooxepinyl such as 2,3,4,5-tetrahydro[1H]oxepin-2-, -3-,        -4-, -5-, -6- or -7-yl, 2,3,4,7-tetrahydro[1H]oxepin-2-, -3-,        -4-, -5-, -6- or -7-yl, 2,3,6,7-tetrahydro[1H]oxepin-2-, -3-,        -4-, -5-, -6- or -7-yl, hexahydroazepin-1-, -2-, -3- or -4-yl,        tetra- and hexahydro-1,3-diazepinyl, tetra- and        hexahydro-1,4-diazepinyl, tetra- and hexahydro-1,3-oxazepinyl,        tetra- and hexahydro-1,4-oxazepinyl, tetra- and        hexahydro-1,3-dioxepinyl, tetra- and hexahydro-1,4-dioxepinyl        and the corresponding ylidene radicals;

a five- or six-membered aromatic heterocycle (=heteroaromatic radical)which contains one, two, three or four heteroatoms from the groupconsisting of oxygen, nitrogen and sulfur, for example 5-memberedheteroaryl which is attached via carbon and contains one to threenitrogen atoms or one or two nitrogen atoms and one sulfur or oxygenatom as ring members, such as 2-furyl, 3-furyl, 2-thienyl, 3-thienyl,2-pyrrolyl, 3-pyrrolyl, 3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl,3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl, 3-pyrazolyl,4-pyrazolyl, 5-pyrazolyl, 2-oxazolyl, 4-oxazolyl, 5-oxazolyl,2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-imidazolyl, 4-imidazolyl,1,2,4-oxadiazol-3-yl, 1,2,4-oxadiazol-5-yl, 1,2,4-thiadiazol-3-yl,1,2,4-thiadiazol-5-yl, 1,2,4-triazol-3-yl, 1,3,4-oxadiazol-2-yl,1,3,4-thiadiazol-2-yl and 1,3,4-triazol-2-yl; 5-membered heteroarylwhich is attached via nitrogen and contains one to three nitrogen atomsas ring members, such as pyrrol-1-yl, pyrazol-1-yl, imidazol-1-yl,1,2,3-triazol-1-yl and 1,2,4-triazol-1-yl; 6-membered heteroaryl, whichcontains one, two or three nitrogen atoms as ring members, such aspyridin-2-yl, pyridin-3-yl, pyridin-4-yl, 3-pyridazinyl, 4-pyridazinyl,2-pyrimidinyl, 4-pyrimidinyl, 5-pyrimidinyl, 2-pyrazinyl,1,3,5-triazin-2-yl and 1,2,4-triazin-3-yl;

The isoxazolo[5,4-b]pyridines of formula I may also be present in theform of the N-oxides and/or their agriculturally useful salts, thenature of the salt being, as a rule, immaterial. In general, suitablesalts are the salts of those cations or the acid addition salts of thoseacids whose cations, or anions, respectively, do not adversely affectthe herbicidal activity of the isoxazolo[5,4-b]pyridines of formula I.

Suitable cations are, in particular, ions of the alkali metals,preferably lithium, sodium or potassium, of the alkaline-earth metals,preferably calcium or magnesium, and of the transition metals,preferably manganese, copper, zinc or iron. Likewise, it is possible touse ammonium as the cation, where, if desired, one to four hydrogenatoms may be replaced by C₁-C₄-alkyl, hydroxy-C₁-C₄-alkyl,hydroxy-C₁-C₄-alkoxy-C₁-C₄-alkyl, phenyl or benzyl, preferably ammonium,dimethylammonium, diisopropylammonium, tetramethylammonium,tetrabutylammonium, 2-(2-hydroxyeth-1-oxy)eth-1-ylammonium,di(2-hydroxyeth-1-yl)ammonium, trimethylbenzylammonium. Others which aresuitable are phosphonium ions, sulfonium ions, preferablytri(C₁-C₄-alkyl)sulfonium or sulfoxonium ions, preferablytri(C₁-C₄-alkyl)sulfoxonium.

Anions of useful acid addition salts are, mainly, chloride, bromide,fluoride, hydrogensulfate, sulfate, dihydrogenphosphate,hydrogenphosphate, nitrate, hydrogencarbonate, carbonate,hexafluorosilicate, hexafluorophosphate, benzoate and the anions ofC₁-C₄-alkanoic acids, preferably formate, acetate, propionate, butyrateor trifluoracetate.

In general, isoxazolo[5,4-b]pyridines of formula I are suitable asherbicides.

Isoxazolo[5,4-b]pyridine compounds of formula I.a (formula I.acorresponds to formula I, wherein R¹ is hydrogen, X is OR⁴ and R⁴ ishydrogen)

or their agriculturally useful salts are particularly useful asherbicides.

Preferred embodiments of the isoxazolo[5,4-b]pyridine compounds offormula I.a are compounds 1.a.1 to 1.a.152 according to table 1, whereineach line of table 1 represents one compound of formula I:

TABLE 1 Isoxazolo[5,4-b]pyridine compounds 1.a.1 to 1.a.152 No. R² R³I.a.1. CH₃ H I.a.2. CH₃ CH₃ I.a.3. CH₃ CH₂CH₃ I.a.4. CH₃ CH₂CH₂CH₃I.a.5. CH₃ CH(CH₃)₂ I.a.6. CH₃ OCH(CH₃)₂ I.a.7. CH₃ CH₂C(CH₃)₃ I.a.8.CH₃ C(CH₃)₃ I.a.9. CH₃ OC(CH₃)₃ I.a.10. CH₃

I.a.11. CH₃

I.a.12. CH₃

I.a.13. CH₃

I.a.14. CH₃ C₆H₅ I.a.15. CH₃ 2-Cl—C₆H₄ I.a.16. CH₃ 2-F—C₆H₄ I.a.17. CH₃2-CH₃O—C₆H₄ I.a.18. CH₃ 2-CF₃—C₆H₄ I.a.19. CH₃ 3-Cl—C₆H₄ I.a.20. CH₃3-F—C₆H₄ I.a.21. CH₃ 3-CH₃O—C₆H₄ I.a.22. CH₃ 3-CF₃—C₆H₄ I.a.23. CH₃4-Cl—C₆H₄ I.a.24. CH₃ 4-F—C₆H₄ I.a.25. CH₃ 4-CH₃O—C₆H₄ I.a.26. CH₃4-CF₃—C₆H₄ I.a.27. CH₃ 2-Cl,3-Cl—C₆H₃ I.a.28. CH₃ 2-Cl,3-F—C₆H₃ I.a.29.CH₃ 2-F,3-Cl—C₆H₃ I.a.30. CH₃ 2-F,3-F—C₆H₃ I.a.31. CH₃ 2-Cl,4-Cl—C₆H₃I.a.32. CH₃ 2-Cl,4-F—C₆H₃ I.a.33. CH₃ 2-F,4-Cl—C₆H₃ I.a.34. CH₃2-F,4-F—C₆H₃ I.a.35. CH₃ 3-Cl,5-Cl—C₆H₃ I.a.36. CH₃ 3-Cl,5-F—C₆H₃I.a.37. CH₃ 3-F,5-Cl—C₆H₃ I.a.38. CH₃ 3-F,5-F—C₆H₃ I.a.39.

H I.a.40.

CH₃ I.a.41.

CH₂CH₃ I.a.42.

CH₂CH₂CH₃ I.a.43.

CH(CH₃)₂ I.a.44.

CH₂CH₂CH₂CH₃ I.a.45.

CH₂CH(CH₃)₂ I.a.46.

C(CH₃)₃ I.a.47.

CF₃ I.a.48.

I.a.49.

I.a.50.

I.a.51.

I.a.52.

C₆H₅ I.a.53.

2-Cl—C₆H₄ I.a.54.

2-F—C₆H₄ I.a.55.

2-CH₃O—C₆H₄ I.a.56.

2-CF₃—C₆H₄ I.a.57.

3-Cl—C₆H₄ I.a.58.

3-F—C₆H₄ I.a.59.

3-CH₃O—C₆H₄ I.a.60.

3-CF₃—C₆H₄ I.a.61.

4-Cl—C₆H₄ I.a.62.

4-F—C₆H₄ I.a.63.

4-CH₃O—C₆H₄ I.a.64.

4-CF₃—C₆H₄ I.a.65.

2-Cl,3-Cl—C₆H₃ I.a.66.

2-Cl,3-F—C₆H₃ I.a.67.

2-F,3-Cl—C₆H₃ I.a.68.

2-F,3-F—C₆H₃ I.a.69.

2-Cl,4-Cl—C₆H₃ I.a.70.

2-Cl,4-F—C₆H₃ I.a.71.

2-F,4-Cl—C₆H₃ I.a.72.

2-F,4-F—C₆H₃ I.a.73.

3-Cl,5-Cl—C₆H₃ I.a.74.

3-Cl,5-F—C₆H₃ I.a.75.

3-F,5-Cl—C₆H₃ I.a.76.

3-F,5-F—C₆H₃ I.a.77.

H I.a.78.

CH₃ I.a.79.

CH₂CH₃ I.a.80.

CH₂CH₂CH₃ I.a.81.

CH(CH₃)₂ I.a.82.

CH₂CH₂CH₂CH₃ I.a.83.

CH₂CH(CH₃)₂ I.a.84.

C(CH₃)₃ I.a.85.

CF₃ I.a.86.

I.a.87.

I.a.88.

I.a.89.

I.a.90.

C₆H₅ I.a.91.

2-Cl—C₆H₄ I.a.92.

2-F—C₆H₄ I.a.93.

2-CH₃O—C₆H₄ I.a.94.

2-CF₃—C₆H₄ I.a.95.

3-Cl—C₆H₄ I.a.96.

3-F—C₆H₄ I.a.97.

3-CH₃O—C₆H₄ I.a.98.

3-CF₃—C₆H₄ I.a.99.

4-Cl—C₆H₄ I.a.100.

4-F—C₆H₄ I.a.101.

4-CH₃O—C₆H₄ I.a.102.

4-CF₃—C₆H₄ I.a.103.

2-Cl,3-Cl—C₆H₃ I.a.104.

2-Cl,3-F—C₆H₃ I.a.105.

2-F,3-Cl—C₆H₃ I.a.106.

2-F,3-F—C₆H₃ I.a.107.

2-Cl,4-Cl—C₆H₃ I.a.108.

2-Cl,4-F—C₆H₃ I.a.109.

2-F,4-Cl—C₆H₃ I.a.110.

2-F,4-F—C₆H₃ I.a.111.

3-Cl,5-Cl—C₆H₃ I.a.112.

3-Cl,5-F—C₆H₃ I.a.113.

3-F,5-Cl—C₆H₃ I.a.114.

3-F,5-F—C₆H₃ I.a.115.

H I.a.116.

CH₃ I.a.117.

CH₂CH₃ I.a.118.

CH₂CH₂CH₃ I.a.119.

CH(CH₃)₂ I.a.120.

CH₂CH₂CH₂CH₃ I.a.121.

CH₂CH(CH₃)₂ I.a.122.

C(CH₃)₃ I.a.123.

CF₃ I.a.124.

I.a.125.

I.a.126.

I.a.127.

I.a.128.

C₆H₅ I.a.129.

2-Cl—C₆H₄ I.a.130.

2-F—C₆H₄ I.a.131.

2-CH₃O—C₆H₄ I.a.132.

2-CF₃—C₆H₄ I.a.133.

3-Cl—C₆H₄ I.a.134.

3-F—C₆H₄ I.a.135.

3-CH₃O—C₆H₄ I.a.136.

3-CF₃—C₆H₄ I.a.137.

4-Cl—C₆H₄ I.a.138.

4-F—C₆H₄ I.a.139.

4-CH₃O—C₆H₄ I.a.140.

4-CF₃—C₆H₄ I.a.141.

2-Cl,3-Cl—C₆H₃ I.a.142.

2-Cl,3-F—C₆H₃ I.a.143.

2-F,3-Cl—C₆H₃ I.a.144.

2-F,3-F—C₆H₃ I.a.145.

2-Cl,4-Cl—C₆H₃ I.a.146.

2-Cl,4-F—C₆H₃ I.a.147.

2-F,4-Cl—C₆H₃ I.a.148.

2-F,4-F—C₆H₃ I.a.149.

3-Cl,5-Cl—C₆H₃ I.a.150.

3-Cl,5-F—C₆H₃ I.a.151.

3-F,5-Cl—C₆H₃ I.a.152.

3-F,5-F—C₆H₃

In addition, the following isoxazolo[5,4-b]pyridine compounds of formulaI are particularly useful as herbicides:

TABLE 2 Isoxazolo[5,4-b]pyridine compounds I.b.1 to I.b.152 Thecompounds 1.b.1 to 1.b.152, which differ from theisoxazolo[5,4-b]pyridine compounds I.a.1 to I.a.152 according to table 1only regarding the variable R⁴, which is CH₃. I.b

TABLE 3 Isoxazolo[5,4-b]pyridine compounds I.c.1 to I.c.152 Thecompounds 1.c.1 to 1.c.152, which differ from theisoxazolo[5,4-b]pyridine compounds I.a.1 to I.a.152 according to table 1only regarding the variable R⁴, which is CH₂OCH₃. I.c

TABLE 4 Isoxazolo[5,4-b]pyridine compounds I.d.1 to I.d.152 Thecompounds 1.d.1 to 1.d.152, which differ from theisoxazolo[5,4-b]pyridine compounds I.a.1 to I.a.152 according to table 1only regarding the variable R⁴, which is CH₂CN. I.d

TABLE 5 Isoxazolo[5,4-b]pyridine compounds I.e.1 to I.e.152 Thecompounds 1.e.1 to 1.e.152, which differ from theisoxazolo[5,4-b]pyridine compounds I.a.1 to I.a.152 according to table 1only regarding the variable R⁴, which is CH₂CH═CH₂. I.e

TABLE 6 Isoxazolo[5,4-b]pyridine compounds I.f.1 to I.f.152 Thecompounds 1.f.1 to 1.f.152, which differ from theisoxazolo[5,4-b]pyridine compounds I.a.1 to I.a.152 according to table 1only regarding the variable R⁴, which is CH₂C≡CH. I.f

According to a preferred embodiment of the invention preference is alsogiven to those isoxazolo[5,4-b]pyridine compounds of formula I, wherein

R¹ is hydrogen, halogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl;

Particularly preferred are those isoxazolo[5,4-b]pyridine compounds offormula I, wherein R¹ is hydrogen.

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein

R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl;and in particular to those isoxazolo[5,4-b]pyridine compounds of formulaI, wherein

-   R² is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;

Very particularly preferred are those isoxazolo[5,4-b]pyridine compoundsof formula I, wherein R² is C₃-C₆-cycloalkyl or C₃-C₆-halocycloalkyl;Most particularly preferred are those isoxazolo[5,4-b]pyridine compoundsof formula I, wherein is R² is cyclopropyl or 1-fluorocyclopropyl.

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein

-   R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, phenyl;    wherein the phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino,    N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;

Particularly preferred are those isoxazolo[5,4-b]pyridine compounds offormula I, wherein R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl,C₃-C₆-cycloalkyl-C₁-C₆-alkyl, C₃-C₆-halocycloalkyl-C₁-C₆-alkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy;

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein

-   X is OR⁴.

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein,

-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl.

Particularly preferred are those isoxazolo[5,4-b]pyridine compounds offormula I, wherein R⁴ is hydrogen, methyl, ethyl, n-propyl, i-propyl,n-butyl, 1-methylpropyl, 2-methylpropoyl, tert.-butyl; Most particularlypreferred are those isoxazolo[5,4-b]pyridine compounds of formula I,wherein is R⁴ is hydrogen;

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein

X is SR⁵.

According to another preferred embodiment of the invention, preferenceis also given to those isoxazolo[5,4-b]pyridine compounds of formula I,wherein,

R⁵ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₂-C₆-alkenyl,C₂-C₆-haloalkenyl, C₂-C₆-alkynyl.

Particularly preferred are those isoxazolo[5,4-b]pyridine compounds offormula I, wherein R⁵ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl,phenyl-C₁-C₆-alkyl; Most particularly preferred are thoseisoxazolo[5,4-b]pyridine compounds of formula I, wherein is R⁵ isC₁-C₆-alkyl, phenyl-C₁-C₆-alkyl;

Particularly useful as herbicides are those isoxazolo[5,4-b]pyridinecompounds of formula I, wherein

-   R¹ is hydrogen;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ and R⁵ can be unsubstituted or substituted with one or more    radicals selected from halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl,    phenyl;-   and their agriculturally useful salts;

Particularly useful as herbicides are those isoxazolo[5,4-b]pyridinecompounds of formula I, wherein

-   R¹ is hydrogen;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₁-C₆-alkoxy,    C₁-C₆-haloalkoxy, phenyl; wherein the phenyl moieties of R³ can be    unsubstituted or substituted with one or more radicals selected from    halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ and R⁵ can be unsubstituted or substituted with one or more    radicals selected from halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl,    phenyl;-   and their agriculturally useful salts;

Particularly useful as herbicides are those isoxazolo[5,4-b]pyridinecompounds of formula I, wherein

-   R¹ is hydrogen;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₁-C₆-alkoxy,    C₁-C₆-haloalkoxy, phenyl; wherein the phenyl moieties of R³ can be    unsubstituted or substituted with one or more radicals selected from    halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl; is most preferably    hydrogen;-   and their agriculturally useful salts;

Particularly useful as herbicides are those isoxazolo[5,4-b]pyridinecompounds of formula I, wherein

-   R¹ is hydrogen;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₁-C₆-alkoxy,    C₁-C₆-haloalkoxy, phenyl; wherein the phenyl moieties of R³ can be    unsubstituted or substituted with one or more radicals selected from    halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is SR⁵;-   R⁵ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, phenyl-C₁-C₆-alkyl; is    most preferably C₁-C₆-alkyl, phenyl-C₁-C₆-alkyl;-   and their agriculturally useful salts;

More particularly useful as herbicides are thoseisoxazolo[5,4-b]pyridine compounds of formula I, wherein

-   R¹ is hydrogen;-   R² is C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl; most preferably    cyclopropyl or 1-fluorocyclopropyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₅)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ and R⁵ can be unsubstituted or substituted with one or more    radicals selected from halogen, C₁-C₄-alkyl, C₁-C₄-alkoxy,    C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl, phenyl; most    preferably hydrogen;-   and their agriculturally useful salts;

More particularly useful as herbicides are thoseisoxazolo[5,4-b]pyridine compounds of formula I, wherein

-   R¹ is hydrogen;-   R² is C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl; most preferably    cyclopropyl or 1-fluorocyclopropyl;-   R³ is C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, phenyl;    wherein the phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl; most preferably    hydrogen;-   and their agriculturally useful salts;

Most particularly useful as herbicides are thoseisoxazolo[5,4-b]pyridine compounds of formula I, wherein

-   R¹ is hydrogen;-   R² is cyclopropyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen;-   and their agriculturally useful salts;

While isoxazolo[5,4-b]pyridine compounds are know in the art, particularisoxazolo[5,4-b]pyridine compounds of formula I are novel. Accordingly,subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is hydrogen, halogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl;-   and their agriculturally useful salts with the exception of    isoxazolo[5,4-b]pyridine compounds of formula I, wherein-   R¹ is hydrogen, R² is cyclopropyl, R³ is CH₃, X is OR⁴ and R⁴ is    hydrogen, C₁-C₆-alkyl, cyanomethyl, or 2-Cl-2-propen-1-yl; and-   R¹ is hydrogen, R² is cyclopropyl, R³ is CH₂C(CH₃)₃, (CH₂)₂CH₃,    CH(CH₃)₂, C(CH₃)₃, cyclopropyl, phenyl, 2-F-phenyl, 4-F-phenyl,    4-methylphenyl, 4-methoxyphenyl, 2-furan-yl,    1,3,5-trimethyl-1H-pyrazol-4-yl, 1-ethyl-5-methyl-1H-pyrazol-4-yl, X    is OR⁴ and R⁴ is hydrogen, methyl or ethyl; and-   R¹ is hydrogen, R² is methyl, R³ is CH₃, CH₂C(CH₃)₃, (CH₂)₂CH₃,    CH(CH₃)₂, C(CH₃)₃, cyclopropyl, phenyl, 4-methylphenyl,    4-methoxyphenyl, 3-methoxyphenyl, 4-fluorophenyl,    3,4-dichlorophenyl, 2-furan-yl, 1,3,5-trimethyl-1H-pyrazol-4-yl,    1-ethyl-5-methyl-1H-pyrazol-4-yl, X is OR⁴ and R⁴ is hydrogen,    methyl or ethyl; and-   R¹ is hydrogen, R² is ethyl, R³ is CH₃, (CH₂)₂CH₃, CH(CH₃)₂,    CH₂C(CH₃)₃, cyclopropyl, 1,3,5-trimethyl-1H-pyrazol-4-yl, X is OR⁴    and R⁴ is hydrogen, methyl or ethyl; and-   R¹ is hydrogen, R² is i-propyl, R³ is CH₃, CH₂C(CH₃)₃, (CH₂)₂CH₃,    CH(CH₃)₂, C(CH₃)₃, cyclopropyl, phenyl, 3-methoxyphenyl, 2-furan-yl;    X is OR⁴ and R⁴ is hydrogen, methyl or ethyl; and-   R¹ is chlorine, R² is methyl, cyclopropyl, R³ is methyl, X is OR⁴    and R⁴ is hydrogen or methyl.

Subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I,

wherein

-   R¹ is hydrogen;-   R² is cyclopropyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₅)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ can be unsubstituted or substituted with one or more radicals    selected from halogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,    C₁-C₄-alkoxycarbonyl, heterocyclyl, phenyl; most preferably    hydrogen;-   and their agriculturally useful salts; with the exception of:    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2,3-dihydro-1H-indol-1-yl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-fluorophenyl)-methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-[4-(methoxycarbonyl)-3,5-dimethyl-1H-pyrrol-2-yl]-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(3-methyl-2-quinoxalinyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2-methoxy-4-methylphenyl)-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-[5-(2-furanyl)-3-isoxazolyl]methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(4-ethoxyphenoxy)ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-(5-phenyl-1,3,4-oxadiazol-2-yl)ethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(5-ethyl-2-thienyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-chloro-2-propen-1-yl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(3,4-dihydro-1(2H)-quinolinyl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(3,4-dimethoxyphenyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(3,4-dihydro-2(1H)-isoquinolinyl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(4-methoxyphenyl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-[2-(3-thienyl)-4-thiazolyl]methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-fluorophenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-pyridinylmethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(3-fluoro-4-methoxyphenyl)-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(4-fluorophenyl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-oxo-2-(pentylamino)ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(5-bromo-2-methoxyphenyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-methyl-2-oxo-2-phenylethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-methyl-2-[(1-methylethyl)amino]-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(6-chloro-3-pyridinyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-amino-1-methyl-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(2-chloro-6-fluorophenyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2-bromophenyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(1,1-dimethylethoxy)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-[2,5-dimethyl-1-(3-methylbutyl)-1H-pyrrol-3-yl]-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2,4-dihydroxyphenyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-[2-(difluoromethoxy)-5-methylphenyl]-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(3-methyl-2-benzofuranyl)-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2-methoxyphenyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(5-methyl-2-thienyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-oxo-2-(2,3,4,5-tetramethylphenyl)ethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-[5-(2-thienyl)-1,3,4-oxadiazol-2-yl]methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methylphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(3-fluoro-4-methoxyphenyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(7-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yl)methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(4-methoxyphenyl)ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(1-butyl-1H-tetrazol-5-yl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(1H-indol-3-yl)-1-methyl-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-benzoxazolylmethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-methylethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-[(1-methylbutyl)amino]-2-oxoethyl        ester;

-   -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-cyanomethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-[3-(methoxycarbonyl)-2-furanyl]methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(3-methyl-5-isoxazolyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(5-chloro-1,2,3-thiadiazol-4-yl)methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-[(1,5-dimethylhexyl)amino]-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2-oxo-1-imidazolidinyl)-2-oxoethyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-methoxy-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-(2,4-dimethoxyphenyl)-2-oxoethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-4-(2-oxo-1-pyrrolidinyl)phenyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,        methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,        ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(3,5-dimethyl-4-isoxazolyl)methyl ester;

-   -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-[3-(2-thienyl)-1,2,4-oxadiazol-5-yl]methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2,3-dichlorophenyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(8-methylimidazo[1,2-a]pyridin-2-yl)methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-(2-ethyl-4-thiazolyl)methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl)-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl)-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl-, ethyl ester    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl)-, ethyl ester;

In a preferred embodiment, subject matter of the present invention arealso isoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is hydrogen;-   R² is cyclopropyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino,    N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl;-   and their agriculturally useful salts; with the exception of:    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-fluorophenyl)-methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-chloro-2-propen-1-yl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-fluorophenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methylphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-methylethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-cyanomethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,        methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,        ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl)-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl)-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl-, ethyl ester    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-, ethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl)-, ethyl ester;

Additionally, subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is halogen;-   R² hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₅)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ and R⁵ can be unsubstituted or substituted with one or more    radicals selected from halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl,    phenyl; most preferably hydrogen;-   and their agriculturally useful salts; with the exception of:    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-6-cyclopropyl-3-methyl-, methyl ester;-   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 5-chloro-3,5-dimethyl;

Additionally, subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is hydroxyl, C₁-C₆-alkyl, C₁-C₆-haloalkyl    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl,    C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    phenyl, phenyl-C₁-C₄-alkyl;-   R² is cyclopropyl;-   R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyloxy-C₁-C₆-alkyl, C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl,    C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl, aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,    N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,    [N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),    N—(C₁-C₆-alkyl)]-aminocarbonyl-C₁-C₆-alkyl,    C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,    C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,    C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,    phenylcarbonyl, heterocyclylcarbonyl-C₁-C₆-alkyl,    phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,    phenyl-C₁-C₆-alkyl; wherein the phenyl and heterocyclyl moieties of    R⁴ and R⁵ can be unsubstituted or substituted with one or more    radicals selected from halogen, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl, heterocyclyl,    phenyl; most preferably hydrogen;    -   and their agriculturally useful salts.

Additionally, subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is hydrogen, halogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl,    C₁-C₄-alkyl-C₃-C₆-cycloalkyl-C₃-C₆-cycloalkenyl,    C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₁-C₄-haloalkyl, C₃-C₆-cycloalkyl,    C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,    C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino,    N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴, SR⁵;-   R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,    C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,    C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl;-   and their agriculturally useful salts; with the exception of:    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-fluorophenyl)-methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-2-chloro-2-propen-1-yl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-fluorophenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methylphenyl)-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-1-methylethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl-cyanomethyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,        methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl)-, methyl        ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dimethyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-methylphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(3-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-fluorophenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(3,4-dichlorophenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        3,6-bis(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(3-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-6-cyclopropyl-3-methyl-, methyl ester;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-3,5-dimethyl;

Additionally, subject matter of the present invention are alsoisoxazolo[5,4-b]pyridine compounds of formula I

wherein

-   R¹ is hydrogen, halogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl;-   R² is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,    C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl;-   R³ hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,    C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,    C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,    C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,    C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,    C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,    heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,    C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,    C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,    N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, phenyl; wherein the    heterocyclyl and phenyl moieties of R³ can be unsubstituted or    substituted with one or more radicals selected from halogen,    hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,    C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,    C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,    C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,    C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, phenyl;-   X is OR⁴;-   R⁴ is hydrogen;-   and their agriculturally useful salts; with the exception of:    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-cyclopropyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dimethyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-methylphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(3-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(4-fluorophenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(3,4-dichlorophenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-methyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-ethyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-propyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        3,6-bis(1-methylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(1,1-dimethylethyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(2,2-dimethylpropyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-cyclopropyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-phenyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(3-methoxyphenyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        6-(1-methylethyl)-3-(2-furanyl);    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-6-cyclopropyl-3-methyl;    -   Isoxazolo[5,4-b]pyridine-4-carboxylic acid,        5-chloro-3,5-dimethyl;

The isoxazolo[5,4-b]pyridines of formula I according to the inventioncan be prepared by standard processes of organic chemistry, for exampleby the following processes:

A compound of formula (C), where R¹ is C₁-C₆-alkyl, C₁-C₆-haloalkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl, C₂-C₆-alkynyl orphenyl-C₁-C₆-alkyl, can be prepared by adding a compound of formula (B),where Z is a halogen, in an inert organic solvent at a temperature from−100° C. to 30° C., preferably at a temperature from −80° C. to 0° C.,most preferably at −78° C., to a compound of formula (A) under an inertgas atmosphere such as argon or nitrogen. The reaction mixture is workedup in a customary manner, for example by mixing with water, separationof the phases, extraction and, if appropriate, chromatographicpurification of the crude product, preferably by extraction.

Suitable solvents are aliphatic hydrocarbons such as pentane, hexane,cyclohexane and mixtures of C₅-C₈-alkanes, aromatic hydrocarbons such astoluene, o-, m- and p-xylene, halogenated hydrocarbons such asdichloromethane, 1,2-dichloroethane, chloroform and chlorobenzene,ethers such as diethyl-ether, diisopropyl-ether, tert.-butylmethylether,dioxane, anisole and tetrahydrofuran, nitriles such as acetonitrile andpropionitrile, as well as dimethylsulfoxide, dimethylformamide andN,N-dimethylacetamide or N-methylpyrrolidone.

Particular preference is given to tetrahydrofuran and diethyl ether. Itis also possible to use mixtures of the solvents mentioned.

The compounds of formula (A) are known from the literature [Duncia, JohnV et al. Bioorganic & Medicinal Chemistry Letters 2008, 18(2), 576-585,and Gao, S. et al. Journal of the American Chemical Society 2010,132(1), 371-383] or they can be prepared in accordance with theliterature cited and/or are commercially available.

The compounds of formula (B) are commercially available.

A compound of formula (C), where R² is 1-fluorocyclopropyl and R¹ ishydrogen is known from the literature [DE 4206917].

A compound of formula (E), where R⁴ is C₁-C₆-alkyl and R¹ is hydrogen,C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl,C₂-C₆-alkenyl, C₂-C₆-alkynyl or phenyl-C₁-C₆-alkyl may be prepared bytreating a mixture of compounds (D) and (C) with a suitable base. Thereaction is conducted in an inert organic solvent at a temperature from−100° C. to 100° C., preferably at a temperature from 0° C. to 80° C.The reaction mixture is worked up in a customary manner, for example bymixing with water, separation of the phases, extraction and, ifappropriate, chromatographic purification of the crude product.

Suitable bases are in general inorganic compounds such as alkali metaland alkaline earth metal hydroxides such as lithium hydroxide, sodiumhydroxide, potassium hydroxide and calcium hydroxide, alkali metal andalkaline earth metal hydrides such as lithium hydride, sodium hydride,potassium hydride and calcium hydride, alkali metal and alkaline earthmetal carbonates such as lithium carbonate, potassium carbonate andcalcium carbonate, as well as alkali metal bicarbonates such as sodiumbicarbonate, alkali metal and alkaline earth metal alkoxides such assodium methoxide, sodium ethoxide, potassium ethoxide, potassiumtert-butoxide, potassium tert-pentoxide and dimethoxymagnesium, andfurthermore organic bases, such as tertiary amines such astrimethylamine, triethylamine, diisopropylethylamine andN-methylpiperidine, pyridine, substituted pyridines such as collidine,lutidine, N-methylmorpholine and 4-dimethylaminopyridine and alsobicyclic amines.

Particular preference is given to sodium methoxide and sodium ethoxide.

The bases are generally employed in equimolar amounts or in excess.

Suitable solvents are ethers such as diethyl ether, diisopropyl ether,tert.-butyl methylether, dioxane, anisole and tetrahydrofuran, nitrilessuch as acetonitrile and propionitrile, alkoholes such as methanol,ethanol, n-propanol, isopropanol, n-butanol and tert.-butanol, as wellas dimethylsulfoxide, dimethylformamide and N,N-dimethylacetamide orN-methylpyrrolidone.

Particular preference is given to methanol or ethanol. It is alsopossible to use mixtures of the solvents mentioned.

Suitable methods required for the preparation of compound of formula (E)are known from the literature [Brecker, L. et al., New J. Chem., 1999,23, 437-446]. The substrates required for the preparation of compound offormula (E) are commercially available

A compound of formula (E) where R¹ is halogen can be prepared accordingto suitable methods known from the literature [Cao, L. et al. Synlett2009, 9, 1445-1448; Still, I. W. J. et al. Journal of Organic Chemistry1981, 46(24), 4911-14 and Banks, R. E. et al. Journal of the ChemicalSociety, Chemical Communications 1994, 3, 343-344].

A compound of formula (G) can be prepared by mixing compound of formula(E) and compound of formula (F) in suitable solvent at a temperature ofbetween 65° C. and 120° C., most preferably at 118° C. After thereaction is completed the reaction mixture is poured into ice/water. Thesolid formed is collected by filtration and dried under high vacuum.

Suitable solvents are

alkoholes such as methanol, ethanol, n-propanol, isopropanol, n-butanoland tert.-butanol, water, carboxylic acids, such as formic acid, glacialacetic acid, as well as dimethylsulfoxide, dimethylformamide andN,N-dimethylacetannide or N-methylpyrrolidone.

Particular preference is given to glacial acetic acid.

It is also possible to use mixtures of the solvents mentioned.

Similar methods are described, for example, Petrosyan, V. A. et al.Russ. Chem. Bull., Int. Ed., 2007, 56, 2186-2188.

Suitable methods required for the preparation of compound of formula (F)are known from the literature [Scott, K. R. European Journal ofMedicinal Chemistry 2002, 37, 635-648, Mitsuhashi, K. Journal ofHeterocyclic Chemistry, 1986, 23(5), 1535-8], EP 0220947, WO 2008034008,Dines, M. B. Tetrahedron Letters 1969, 54, 4817-4819; Koichi, M.Nitriles. IV. Synthesis of isoxazoles and pyrazoles from somethree-carbon nitriles, Takeda Kenkyushoho 1971, 30(3), 475-92. Some ofthe compounds of formula (F) are commercially available.

A compound of formula (G) where R¹ is hydroxyl,C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy can be preparedfrom a compound of formula (G) where R¹ is halogen according to suitablemethods known from the literature, for example: Dejardin, J. V. et. al.Bulletin de la Societe Chimique de France 1976, 3-4, Pt. 2, 530-532,Ouyang, X. et. al. Bioorganic & Medicinal Chemistry Letters 2005,15(23), 5154-5159 and Magee, T. V. et. al. Journal of MedicinalChemistry 2009, 52(23), 7446-7457. A compound of formula (G) where R¹ ishydrogen and R³ is halogen can be prepared by mixing a compound offormula (G) where R¹ is hydrogen and R³ is OH with pyridine hydrohalide,acide (most preferably H₃PO₄) and phosphoroxyhalide and stirring it at atemperature between 50° C. and 120° C., most preferably at 90° C. for1-5 h. The excess of phosphoroxyhalide is evaporated under high vacuum.The reaction mixture is worked up in a customary manner, for example byadding a suitable solvent and aqueus solution of alkali metalbicarbonate, separation of the phases, extraction and, if appropriate,chromatographic purification of the crude product.

Suitable solvents are ethyl acetate, dichloromethane, diethyl ether,chloroform, tertbuthylmethyl ether, diisopropyl ether. Suitable alkalimetal bicarbonates are sodium bicarbonate, potassium bicarbonate,calcium bicarbonate.

A compound of formula (G) where R¹ is hydrogen and R³ is C₁-C₆-alkoxycan be prepared by adding a C₁-C₆-alkyl alcohol and a compound offormula (G) where R¹ is hydrogen and R³ is OH to the previously preparedstirred solution of di-C₁-C₆-alkyl azodicarboxylate and triarylphosphine(most preferably triphenylphosphine) in a suitable solvent (preferablytetrahydrofuran) at a temperature between −20° C. and 25° C., mostpreferably at 0° C. The reaction is conducted at a temperature between−20° C. to 100° C., preferably at a temperature between 40° C. to 80° C.The reaction mixture is worked up in a customary manner, for example byremoving the solvent under vacuum and chromatographic purification ofthe crude product.

Suitable solvents are ethers such as diethyl-ether, diisopropyl-ether,tert.-butylmethylether, dioxane, anisole and tetrahydrofuran. Particularpreference is given to tetrahydrofuran and diethyl ether. It is alsopossible to use mixtures of the solvents mentioned.

A compound of formula (H) can be prepared from a compound of formula (G)by hydrolysis in a presence of a suitable acid or base catalyst in asuitable solvent at temperatures between 0° C. and 80° C., mostpreferably at 25° C., under conventional heating or under microwaveirradiation [see, for example, Carrigan, C. N. J. Med. Chem. 2002, 45,2260-2276 and Ghosh, P. Journal of Teaching and Research in Chemistry2008, 15(2), 54-57].

Suitable acid catalyst are:

anorganic acids like hydrofluoric acid, hydrochloric acid, hydrobromicacid, perchloric acid, sulphuric acid.

Particular preference is given to hydrochloric acid and sulphuric acid.

The acids are generally employed in catalytic amounts, however they canalso be employed in equimolar amounts or in excess.

Suitable base catalyst are:

alkali metal and alkaline earth metal hydroxides such as lithiumhydroxide, sodium hydroxide, potassium hydroxide and calcium hydroxide.

Particular preference is given to metal hydroxides such as sodiumhydroxide.

The bases are generally employed in catalytic amounts, however they canalso be employed in equimolar amounts or in excess.

Suitable solvents are ethers such as diethyl ether, diisopropyl ether,tert.-butyl methylether, dioxane, anisole and tetrahydrofuran, water,alkoholes such as methanol, ethanol, n-propanol, isopropanol, n-butanoland tert.-butanol, as well as dimethylsulfoxide.

Particular preference is given to tetrahydrofuran.

It is also possible to use mixtures of the solvents mentioned.

A compound of formula (H) can be esterified, thioesterified, transformedto an amide or an acid halide, preferably acid chloride, of a compoundof formula (I) where X is OR⁴ (see, for example, Arnab, P. et. al.Angewandte Chemie, International Edition 2010, 49(8), 1492-1495), SR⁵(see, for example, Silvestri, M. A. et. al. Journal of MedicinalChemistry 2004, 47(12), 3149-3162), NR⁶R⁷ (see, for example, Kuhn, B.et. al. Journal of Medicinal Chemistry 2010, 53(6), 2601-2611) understandard conditions.

The isoxazolo[5,4-b]pyridines of formula I are suitable as herbicides.They are suitable as such or as an appropriately formulated composition(herbicidal composition). As used in this application, the terms“formulated composition” and “herbicidal composition” are synonyms.

The herbicidal compositions comprising the isoxazolo[5,4-b]pyridines offormula I control vegetation on non-crop areas very efficiently,especially at high rates of application. They act against broad-leavedweeds and grass weeds in crops such as wheat, rice, maize, soya andcotton without causing any significant damage to the crop plants. Thiseffect is mainly observed at low rates of application.

Depending on the application method in question, theisoxazolo[5,4-b]pyridines of formula I or compositions comprising themcan additionally be employed in a further number of crop plants foreliminating undesirable plants. Examples of suitable crops are thefollowing:

Allium cepa, Ananas comosus, Arachis hypogaea, Asparagus officinalis,Avena sativa, Beta vulgaris spec. altissima, Beta vulgaris spec. rapa,Brassica napus var. napus, Brassica napus var. napobrassica, Brassicarapa var. silvestris, Brassica oleracea, Brassica nigra, Camelliasinensis, Carthamus tinctorius, Carya illinoinensis, Citrus limon,Citrus sinensis, Coffea arabica (Coffea canephora, Coffea liberica),Cucumis sativus, Cynodon dactylon, Daucus carota, Elaeis guineensis,Fragaria vesca, Glycine max, Gossypium hirsutum, (Gossypium arboreum,Gossypium herbaceum, Gossypium vitifolium), Helianthus annuus, Heveabrasiliensis, Hordeum vulgare, Humulus lupulus, Ipomoea batatas, Juglansregia, Lens culinaris, Linum usitatissimum, Lycopersicon lycopersicum,Malus spec., Manihot esculenta, Medicago sativa, Musa spec., Nicotianatabacum (N. rustica), Olea europaea, Oryza sativa, Phaseolus lunatus,Phaseolus vulgaris, Picea abies, Pinus spec., Pistacia vera, Pisumsativum, Prunus avium, Prunus persica, Pyrus communis, Prunus armeniaca,Prunus cerasus, Prunus dulcis and Prunus domestica, Ribes sylvestre,Ricinus communis, Saccharum officinarum, Secale cereale, Sinapis alba,Solanum tuberosum, Sorghum bicolor (s. vulgare), Theobroma cacao,Trifolium pratense, Triticum aestivum, Triticale, Triticum durum, Viciafaba, Vitis vinifera and Zea mays.

Preferred crops are the following: Arachis hypogaea, Beta vulgaris spec.altissima, Brassica napus var. napus, Brassica oleracea, Citrus limon,Citrus sinensis, Coffea arabica (Coffea canephora, Coffea liberica),Cynodon dactylon, Glycine max, Gossypium hirsutum, (Gossypium arboreum,Gossypium herbaceum, Gossypium vitifolium), Helianthus annuus, Hordeumvulgare, Juglans regia, Lens culinaris, Linum usitatissimum,Lycopersicon lycopersicum, Malus spec., Medicago sativa, Nicotianatabacum (N. rustica), Olea europaea, Oryza sativa, Phaseolus lunatus,Phaseolus vulgaris, Pistacia vera, Pisum sativum, Prunus dulcis,Saccharum officinarum, Secale cereale, Solanum tuberosum, Sorghumbicolor (s. vulgare), Triticale, Triticum aestivum, Triticum durum,Vicia faba, Vitis vinifera and Zea mays.

The isoxazolo[5,4-b]pyridines of formula I according to the inventioncan also be used in genetically modified plants. The term “geneticallymodified plants” is to be understood as plants, which genetic materialhas been modified by the use of recombinant DNA techniques in a way thatunder natural circumstances it cannot readily be obtained by crossbreeding, mutations or natural recombination. Typically, one or moregenes have been integrated into the genetic material of a geneticallymodified plant in order to improve certain properties of the plant. Suchgenetic modifications also include but are not limited to targetedpost-transtional modification of protein(s), oligo- or poly-peptidese.g. by glycosylation or polymer additions such as prenylated,acetylated or farnesylated moieties or PEG moieties.

Plants that have been modified by breeding, mutagenesis or geneticengineering, e.g. have been rendered tolerant to applications ofspecific classes of herbicides, such as auxin herbicides such as dicambaor 2,4-D; bleacher herbicides such as hydroxyphenylpyruvate dioxygenase(HPPD) inhibitors or phytoene desaturase (PDS) inhibitors; acetolactatesynthase (ALS) inhibitors such as sulfonyl ureas or imidazolinones;enolpyruvyl shikimate 3-phosphate synthase (EPSP) inhibitors such asglyphosate; glutamine synthetase (GS) inhibitors such as glufosinate;protoporphyrinogen-IX oxidase inhibitors; lipid biosynthesis inhibitorssuch as acetyl CoA carboxylase (ACCase) inhibitors; or oxynil (i. e.bromoxynil or ioxynil) herbicides as a result of conventional methods ofbreeding or genetic engineering; furthermore, plants have been maderesistant to multiple classes of herbicides through multiple geneticmodifications, such as resistance to both glyphosate and glufosinate orto both glyphosate and a herbicide from another class such as ALSinhibitors, HPPD inhibitors, auxin herbicides, or ACCase inhibitors.These herbicide resistance technologies are, for example, described inPest Management Science 61, 2005, 246; 61, 2005, 258; 61, 2005, 277; 61,2005, 269; 61, 2005, 286; 64, 2008, 326; 64, 2008, 332; Weed Science 57,2009, 108; Australian Journal of Agricultural Research 58, 2007, 708;Science 316, 2007, 1185; and references quoted therein. Severalcultivated plants have been rendered tolerant to herbicides byconventional methods of breeding (mutagenesis), e.g. Clearfield® summerrape (Canola, BASF SE, Germany) being tolerant to imidazolinones, e.g.imazamox, or ExpressSun® sunflowers (DuPont, USA) being tolerant tosulfonyl ureas, e.g. tribenuron. Genetic engineering methods have beenused to render cultivated plants such as soybean, cotton, corn, beetsand rape, tolerant to herbicides such as glyphosate, imidazolinones andglufosinate, some of which are under development or commerciallyavailable under the brands or trade names RoundupReady® (glyphosatetolerant, Monsanto, USA), Cultivance® (imidazolinone tolerant, BASF SE,Germany) and LibertyLink® (glufosinate tolerant, Bayer CropScience,Germany).

Furthermore, plants are also covered that are by the use of recombinantDNA techniques capable to synthesize one or more insecticidal proteins,especially those known from the bacterial genus Bacillus, particularlyfrom Bacillus thuringiensis, such as ä-endotoxins, e.g. CryIA(b),CryIA(c), CryIF, CryIF(a2), CryIIA(b), CryIIIA, CryIIIB(b1) or Cry9c;vegetative insecticidal proteins (VIP), e.g. VIP1, VIP2, VIP3 or VIP3A;insecticidal proteins of bacteria colonizing nematodes, e.g.Photorhabdus spp. or Xenorhabdus spp.; toxins produced by animals, suchas scorpion toxins, arachnid toxins, wasp toxins, or otherinsect-specific neurotoxins; toxins produced by fungi, suchStreptomycetes toxins, plant lectins, such as pea or barley lectins;agglutinins; proteinase inhibitors, such as trypsin inhibitors, serineprotease inhibitors, patatin, cystatin or papain inhibitors;ribosome-inactivating proteins (RIP), such as ricin, maize-RIP, abrin,luffin, saporin or bryodin; steroid metabolism enzymes, such as3-hydroxy-steroid oxidase, ecdysteroid-IDP-glycosyl-transferase,cholesterol oxidases, ecdysone inhibitors or HMG-CoA-reductase; ionchannel blockers, such as blockers of sodium or calcium channels;juvenile hormone esterase; diuretic hormone receptors (helicokininreceptors); stilben synthase, bibenzyl synthase, chitinases orglucanases. In the context of the present invention these insecticidalproteins or toxins are to be under-stood expressly also as pre-toxins,hybrid proteins, truncated or otherwise modified proteins. Hybridproteins are characterized by a new combination of protein domains,(see, e.g. WO 02/015701). Further examples of such toxins or geneticallymodified plants capable of synthesizing such toxins are dis-closed,e.g., in EP-A 374 753, WO 93/007278, WO 95/34656, EP-A 427 529, EP-A 451878, WO 03/18810 and WO 03/52073. The methods for producing suchgenetically modified plants are generally known to the person skilled inthe art and are described, e.g. in the publications mentioned above.These insecticidal proteins contained in the genetically modified plantsimpart to the plants producing these proteins tolerance to harmful pestsfrom all taxonomic groups of athropods, especially to beetles(Coeloptera), two-winged insects (Diptera), and moths (Lepidoptera) andto nematodes (Nematoda). Genetically modified plants capable tosynthesize one or more insecticidal proteins are, e.g., described in thepublications mentioned above, and some of which are commerciallyavailable such as YieldGard® (corn cultivars producing the Cry1Abtoxin), YieldGard® Plus (corn cultivars producing Cry1Ab and Cry3Bb1toxins), Starlink® (corn cultivars producing the Cry9c toxin), Herculex®RW (corn cultivars producing Cry34Ab1, Cry35Ab1 and the enzymePhosphinothricin-N-Acetyltransferase [PAT]); NuCOTN® 33B (cottoncultivars producing the Cry1Ac toxin), Bollgard® I (cotton cultivarsproducing the Cry1Ac toxin), Bollgard® II (cotton cultivars producingCry1Ac and Cry2Ab2 toxins); VIPCOT® (cotton cultivars producing aVIP-toxin); NewLeaf® (potato cultivars producing the Cry3A toxin);BtXtra®, NatureGard®, KnockOut®, BiteGard®, Protecta®, Bt11 (e.g.Agrisure® CB) and Bt176 from Syngenta Seeds SAS, France, (corn cultivarsproducing the Cry1Ab toxin and PAT enyzme), MIR604 from Syngenta SeedsSAS, France (corn cultivars producing a modified version of the Cry3Atoxin, c.f. WO 03/018810), MON 863 from Monsanto Europe S.A., Belgium(corn cultivars produ-cing the Cry3Bb1 toxin), IPC 531 from MonsantoEurope S.A., Belgium (cotton cultivars producing a modified version ofthe Cry1Ac toxin) and 1507 from Pioneer Overseas Corporation, Belgium(corn cultivars producing the Cry1F toxin and PAT enzyme).

Furthermore, plants are also covered that are by the use of recombinantDNA techniques capable to synthesize one or more proteins to in-creasethe resistance or tolerance of those plants to bacterial, viral orfungal pathogens. Examples of such proteins are the so-called“pathogenesis-related proteins” (PR proteins, see, e.g. EP-A 392 225),plant disease resistance genes (e.g. potato culti-vars, which expressresistance genes acting against Phytophthora infestans derived from themexican wild potato Solanum bulbocastanum) or T4-lyso-zym (e.g. potatocultivars capable of synthesizing these proteins with increasedresistance against bacteria such as Erwinia amylvora). The methods forproducing such genetically modi-fied plants are generally known to theperson skilled in the art and are described, e.g. in the publicationsmentioned above.

Furthermore, plants are also covered that are by the use of recombinantDNA techniques capable to synthesize one or more proteins to increasethe productivity (e.g. bio mass production, grain yield, starch content,oil content or protein content), tolerance to drought, salinity or othergrowth-limiting environ-mental factors or tolerance to pests and fungal,bacterial or viral pathogens of those plants.

Furthermore, plants are also covered that contain by the use ofrecombinant DNA techniques a modified amount of substances of content ornew substances of content, specifically to improve human or animalnutrition, e.g. oil crops that produce healthpromoting long-chainomega-3 fatty acids or unsaturated omega-9 fatty acids (e.g. Nexera®rape, DOW Agro Sciences, Canada).

Furthermore, plants are also covered that contain by the use ofrecombinant DNA techniques a modified amount of substances of content ornew substances of content, specifically to improve raw materialproduction, e.g. potatoes that produce increased amounts of amylopectin(e.g. Amflora® potato, BASF SE, Germany).

Furthermore, it has been found that the isoxazolo[5,4-b]pyridines of theformula I are also suitable for the defoliation and/or desiccation ofplant parts, for which crop plants such as cotton, potato, oilseed rape,sunflower, soybean or field beans, in particular cotton, are suitable.In this regard, compositions for the desiccation and/or defoliation ofplants, processes for preparing these compositions and methods fordesiccating and/or defoliating plants using theisoxazolo[5,4-b]pyridines of formula I have been found.

As desiccants, the isoxazolo[5,4-b]pyridines of formula I areparticularly suitable for desiccating the above-ground parts of cropplants such as potato, oilseed rape, sunflower and soybean, but alsocereals. This makes possible the fully mechanical harvesting of theseimportant crop plants.

Also of economic interest is to facilitate harvesting, which is madepossible by concentrating within a certain period of time thedehiscence, or reduction of adhesion to the tree, in citrus fruit,olives and other species and varieties of pernicious fruit, stone fruitand nuts. The same mechanism, i.e. the promotion of the development ofabscission tissue between fruit part or leaf part and shoot part of theplants is also essential for the controlled defoliation of usefulplants, in particular cotton.

Moreover, a shortening of the time interval in which the individualcotton plants mature leads to an increased fiber quality afterharvesting.

The isoxazolo[5,4-b]pyridines of formula I, or the herbicidalcompositions comprising the isoxazolo[5,4-b]pyridines of formula I, canbe used, for example, in the form of ready-to-spray aqueous solutions,powders, suspensions, also highly concentrated aqueous, oily or othersuspensions or dispersions, emulsions, oil dispersions, pastes, dusts,materials for broadcasting, or granules, by means of spraying,atomizing, dusting, spreading, watering or treatment of the seed ormixing with the seed. The use forms depend on the intended purpose; inany case, they should ensure the finest possible distribution of theactive ingredients according to the invention.

The herbicidal compositions comprise an herbicidal effective amount ofat least one isoxazolo[5,4-b]pyridines of formula I and auxiliarieswhich are customary for the formulation of crop protection agents.

Examples of auxiliaries customary for the formulation of crop protectionagents are inert auxiliaries, solid carriers, surfactants (such asdispersants, protective colloids, emulsifiers, wetting agents andtackifiers), organic and inorganic thickeners, bactericides, antifreezeagents, antifoams, optionally colorants and, for seed formulations,adhesives.

The person skilled in the art is sufficiently familiar with the recipesfor such formulations.

Examples of thickeners (i.e. compounds which impart to the formulationmodified flow properties, i.e. high viscosity in the state of rest andlow viscosity in motion) are polysaccharides, such as xanthan gum(Kelzan® from Kelco), Rhodopol®23 (Rhone Poulenc) or Veegum® (from R.T.Vanderbilt), and also organic and inorganic sheet minerals, such asAttaclay® (from Engelhardt).

Examples of antifoams are silicone emulsions (such as, for example,Silikon SRE, Wacker or Rhodorsil® from Rhodia), long-chain alcohols,fatty acids, salts of fatty acids, organofluorine compounds and mixturesthereof.

Bactericides can be added for stabilizing the aqueous herbicidalformulations. Examples of bactericides are bactericides based ondiclorophen and benzyl alcohol hemiformal (Proxel® from ICI or Acticide®RS from Thor Chemie and Kathon® MK from Rohm & Haas), and alsoisothiazolinone derivates, such as alkylisothiazolinones andbenzisothiazolinones (Acticide MBS from Thor Chemie).

Examples of antifreeze agents are ethylene glycol, propylene glycol,urea or glycerol.

Examples of colorants are both sparingly water-soluble pigments andwater-soluble dyes. Examples which may be mentioned are the dyes knownunder the names Rhodamin B, C.I. Pigment Red 112 and C.I. Solvent Red 1,and also pigment blue 15:4, pigment blue 15:3, pigment blue 15:2,pigment blue 15:1, pigment blue 80, pigment yellow 1, pigment yellow 13,pigment red 112, pigment red 48:2, pigment red 48:1, pigment red 57:1,pigment red 53:1, pigment orange 43, pigment orange 34, pigment orange5, pigment green 36, pigment green 7, pigment white 6, pigment brown 25,basic violet 10, basic violet 49, acid red 51, acid red 52, acid red 14,acid blue 9, acid yellow 23, basic red 10, basic red 108.

Examples of adhesives are polyvinylpyrrolidone, polyvinyl acetate,polyvinyl alcohol and tylose.

Suitable inert auxiliaries are, for example, the following:

mineral oil fractions of medium to high boiling point, such as keroseneand diesel oil, furthermore coal tar oils and oils of vegetable oranimal origin, aliphatic, cyclic and aromatic hydrocarbons, for exampleparaffin, tetrahydronaphthalene, alkylated naphthalenes and theirderivatives, alkylated benzenes and their derivatives, alcohols such asmethanol, ethanol, propanol, butanol and cyclohexanol, ketones such ascyclohexanone or strongly polar solvents, for example amines such asN-methylpyrrolidone, and water.

Suitable carriers include liquid and solid carriers.

Liquid carriers include e.g. non-aqeuos solvents such as cyclic andaromatic hydrocarbons, e.g. paraffins, tetrahydronaphthalene, alkylatednaphthalenes and their derivatives, alkylated benzenes and theirderivatives, alcohols such as methanol, ethanol, propanol, butanol andcyclohexanol, ketones such as cyclohexanone, strongly polar solvents,e.g. amines such as N-methylpyrrolidone, and water as well as mixturesthereof.

Solid carriers include e.g. mineral earths such as silicas, silica gels,silicates, talc, kaolin, limestone, lime, chalk, bole, loess, clay,dolomite, diatomaceous earth, calcium sulfate, magnesium sulfate andmagnesium oxide, ground synthetic materials, fertilizers such asammonium sulfate, ammonium phosphate, ammonium nitrate and ureas, andproducts of vegetable origin, such as cereal meal, tree bark meal, woodmeal and nutshell meal, cellulose powders, or other solid carriers.

Suitable surfactants (adjuvants, wetting agents, tackifiers, dispersantsand also emulsifiers) are the alkali metal salts, alkaline earth metalsalts and ammonium salts of aromatic sulfonic acids, for examplelignosulfonic acids (e.g. Borrespers-types, Borregaard), phenolsulfonicacids, naphthalenesulfonic acids (Morwet types, Akzo Nobel) anddibutylnaphthalenesulfonic acid (Nekal types, BASF AG), and of fattyacids, alkyl- and alkylarylsulfonates, alkyl sulfates, lauryl ethersulfates and fatty alcohol sulfates, and salts of sulfated hexa-, hepta-and octadecanols, and also of fatty alcohol glycol ethers, condensatesof sulfonated naphthalene and its derivatives with formaldehyde,condensates of naphthalene or of the naphthalenesulfonic acids withphenol and formaldehyde, polyoxyethylene octylphenol ether, ethoxylatedisooctyl-, octyl- or nonylphenol, alkylphenyl or tributylphenylpolyglycol ether, alkylaryl polyether alcohols, isotridecyl alcohol,fatty alcohol/ethylene oxide condensates, ethoxylated castor oil,polyoxyethylene alkyl ethers or polyoxypropylene alkyl ethers, laurylalcohol polyglycol ether acetate, sorbitol esters, lignosulfite wasteliquors and proteins, denaturated proteins, polysaccharides (e.g.methylcellulose), hydrophobically modified starches, polyvinyl alcohol(Mowiol types Clariant), polycarboxylates (BASF AG, Sokalan types),polyalkoxylates, polyvinylamine (BASF AG, Lupamine types),polyethyleneimine (BASF AG, Lupasol types), polyvinylpyrrolidone andcopolymers thereof.

Powders, materials for broadcasting and dusts can be prepared by mixingor concomitant grinding the active ingredients together with a solidcarrier.

Granules, for example coated granules, impregnated granules andhomogeneous granules, can be prepared by binding the active ingredientsto solid carriers.

Aqueous use forms can be prepared from emulsion concentrates,suspensions, pastes, wettable powders or water-dispersible granules byadding water.

To prepare emulsions, pastes or oil dispersions, theisoxazolo[5,4-b]pyridines of formula I, either as such or dissolved inan oil or solvent, can be homogenized in water by means of a wettingagent, tackifier, dispersant or emulsifier. Alternatively, it is alsopossible to prepare concentrates comprising active compound, wettingagent, tackifier, dispersant or emulsifier and, if desired, solvent oroil, which are suitable for dilution with water.

The concentrations of the isoxazolo[5,4-b]pyridines of formula I in theready-to-use preparations (formulations) can be varied within wideranges. In general, the formulations comprise approximately from 0.001to 98% by weight, preferably 0.01 to 95% by weight of at least oneactive ingredient. The active ingredients are employed in a purity offrom 90% to 100%, preferably 95% to 100% (according to NMR spectrum).

In the formulation of the isoxazolo[5,4-b]pyridines of formula Iaccording to the present invention the active ingredients, e.g. theisoxazolo[5,4-b]pyridines of formula I, are present in suspended,emulsified or dissolved form. The formulation according to the inventioncan be in the form of aqueous solutions, powders, suspensions, alsohighlyconcentrated aqueous, oily or other suspensions or dispersions,aqueous emulsions, aqueous microemulsions, aqueous suspo-emulsions, oildispersions, pastes, dusts, materials for spreading or granules.

The isoxazolo[5,4-b]pyridines of formula I according to the presentinvention can, for example, be formulated as follows:

1. Products for dilution with waterA Water-soluble concentrates

10 parts by weight of active compound are dissolved in 90 parts byweight of water or a water-soluble solvent. As an alternative, wettersor other adjuvants are added. The active compound dissolves upondilution with water. This gives a formulation with an active compoundcontent of 10% by weight.

B Dispersible concentrates

20 parts by weight of active compound are dissolved in 70 parts byweight of cyclohexanone with addition of 10 parts by weight of adispersant, for example polyvinylpyrrolidone. Dilution with water givesa dispersion. The active compound content is 20% by weight.

C Emulsifiable concentrates

15 parts by weight of active compound are dissolved in 75 parts byweight of an organic solvent (eg. alkylaromatics) with addition ofcalcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case5 parts by weight). Dilution with water gives an emulsion. Theformulation has an active compound content of 15% by weight.

D Emulsions

25 parts by weight of active compound are dissolved in 35 parts byweight of an organic solvent (eg. alkylaromatics) with addition ofcalcium dodecylbenzenesulfonate and castor oil ethoxylate (in each case5 parts by weight). This mixture is introduced into 30 parts by weightof water by means of an emulsifier (Ultraturrax) and made into ahomogeneous emulsion. Dilution with water gives an emulsion. Theformulation has an active compound content of 25% by weight.

E Suspensions

In an agitated ball mill, 20 parts by weight of active compound arecomminuted with addition of 10 parts by weight of dispersants andwetters and 70 parts by weight of water or an organic solvent to give afine active compound suspension. Dilution with water gives a stablesuspension of the active compound. The active compound content in theformulation is 20% by weight.

F Water-dispersible granules and water-soluble granules

50 parts by weight of active compound are ground finely with addition of50 parts by weight of dispersants and wetters and made intowater-dispersible or water-soluble granules by means of technicalappliances (for example extrusion, spray tower, fluidized bed). Dilutionwith water gives a stable dispersion or solution of the active compound.The formulation has an active compound content of 50% by weight.

G Water-dispersible powders and water-soluble powders

75 parts by weight of active compound are ground in a rotor-stator millwith addition of 25 parts by weight of dispersants, wetters and silicagel. Dilution with water gives a stable dispersion or solution of theactive compound. The active compound content of the formulation is 75%by weight.

H Gel formulations

In a ball mill, 20 parts by weight of active compound, 10 parts byweight of dispersant, 1 part by weight of gelling agent and 70 parts byweight of water or of an organic solvent are mixed to give a finesuspension. Dilution with water gives a stable suspension with activecompound content of 20% by weight.

2. Products to be applied undiluted

I Dusts

5 parts by weight of active compound are ground finely and mixedintimately with 95 parts by weight of finely divided kaolin. This givesa dusting powder with an active compound content of 5% by weight.

J Granules (GR, FG, GG, MG)

0.5 parts by weight of active compound are ground finely and associatedwith 99.5 parts by weight of carriers. Current methods here areextrusion, spray-drying or the fluidized bed. This gives granules to beapplied undiluted with an active compound content of 0.5% by weight.

K ULV solutions (UL)

10 parts by weight of active compound are dissolved in 90 parts byweight of an organic solvent, for example xylene. This gives a productto be applied undiluted with an active compound content of 10% byweight.

Aqueous use forms can be prepared from emulsion concentrates,suspensions, pastes, wettable powders or water-dispersible granules byadding water.

The isoxazolo[5,4-b]pyridines of formula I or the herbicidalcompositions comprising them can be applied pre-, post-emergence orpre-plant, or together with the seed of a crop plant. It is alsopossible to apply the herbicidal composition or active compounds byapplying seed, pretreated with the herbicidal compositions or activecompounds, of a crop plant. If the active ingredients are less welltolerated by certain crop plants, application techniques may be used inwhich the herbicidal compositions are sprayed, with the aid of thespraying equipment, in such a way that as far as possible they do notcome into contact with the leaves of the sensitive crop plants, whilethe active ingredients reach the leaves of undesirable plants growingunderneath, or the bare soil surface (post-directed, lay-by).

In a further embodiment, the isoxazolo[5,4-b]pyridines of formula I orthe herbicidal compositions can be applied by treating seed. Thetreatment of seeds comprises essentially all procedures familiar to theperson skilled in the art (seed dressing, seed coating, seed dusting,seed soaking, seed film coating, seed multilayer coating, seedencrusting, seed dripping and seed pelleting) based on theisoxazolo[5,4-b]pyridines of formula I according to the invention or thecompositions prepared therefrom. Here, the herbicidal compositions canbe applied diluted or undiluted.

The term “seed” comprises seed of all types, such as, for example,corns, seeds, fruits, tubers, seedlings and similar forms. Here,preferably, the term seed describes corns and seeds.

The seed used can be seed of the useful plants mentioned above, but alsothe seed of transgenic plants or plants obtained by customary breedingmethods.

The rates of application of the active isoxazolo[5,4-b]pyridines offormula I according to the present invention (total amount ofisoxazolo[5,4-b]pyridines of formula I) are from 0.1 g/ha to 3000 g/ha,preferably 10 g/ha to 1000 g/ha of active substance (a.s.), depending onthe control target, the season, the target plants and the growth stage.

In another preferred embodiment of the invention, the application ratesof the isoxazolo[5,4-b]pyridines of formula I are in the range from 0.1g/ha to 5000 g/ha and preferably in the range from 1 g/ha to 2500 g/haor from 5 g/ha to 2000 g/ha of active substance (a.s.).

In another preferred embodiment of the invention, the application rateof the isoxazolo[5,4-b]pyridines of formula I is 0.1 to 1000 g/ha,preferably 1 to 750 g/ha, more preferably 5 to 500 g/ha, of activesubstance.

To treat the seed, the isoxazolo[5,4-b]pyridines I are generallyemployed in amounts of from 0.001 to 10 kg per 100 kg of seed.

To widen the spectrum of action and to achieve synergistic effects, theisoxazolo[5,4-b]pyridines of the formula I may be mixed with a largenumber of representatives of other herbicidal or growth-regulatingactive ingredient groups and then applied concomitantly. Suitablecomponents for mixtures are, for example, 1,2,4-thiadiazoles,1,3,4-thiadiazoles, amides, aminophosphoric acid and its derivatives,aminotriazoles, anilides, (het)aryloxyalkanoic acids and theirderivatives, benzoic acid and its derivatives, benzothiadiazinones,2-aroyl-1,3-cyclohexanediones, 2-hetaroyl-1,3-cyclohexanediones, hetarylaryl ketones, benzylisoxazolidinones, meta-CF₃-phenyl derivatives,carbamates, quinolinecarboxylic acid and its derivatives,chloroacetanilides, cyclohexenone oxime ether derivatives, diazines,dichloropropionic acid and its derivatives, dihydrobenzofurans,dihydrofuran-3-ones, dinitroanilines, dinitrophenols, diphenyl ethers,dipyridyls, halocarboxylic acids and their derivatives, ureas,3-phenyluracils, imidazoles, imidazolinones,N-phenyl-3,4,5,6-tetrahydrophthalinnides, oxadiazoles, oxiranes,phenols, aryloxy- and hetaryloxyphenoxypropionic esters, phenylaceticacid and its derivatives, 2-phenylpropionic acid and its derivatives,pyrazoles, phenylpyrazoles, pyridazines, pyridinecarboxylic acid and itsderivatives, pyrimidyl ethers, sulfonamides, sulfonylureas, triazines,triazinones, triazolinones, triazolecarboxamides, uracils, phenylpyrazolines and isoxazolines and derivatives thereof.

It may furthermore be beneficial to apply the isoxazolo[5,4-b]pyridinesof formula I alone or in combination with other herbicides, or else inthe form of a mixture with other crop protection agents, for exampletogether with agents for controlling pests or phytopathogenic fungi orbacteria. Also of interest is the miscibility with mineral saltsolutions, which are employed for treating nutritional and trace elementdeficiencies. Other additives such as non-phytotoxic oils and oilconcentrates may also be added.

Moreover, it may be useful to apply the isoxazolo[5,4-b]pyridines offormula I in combination with safeners. Safeners are chemical compoundswhich prevent or reduce damage on useful plants without having a majorimpact on the herbicidal action of the isoxazolo[5,4-b]pyridines offormula I towards unwanted plants. They can be applied either beforesowings (e.g. on seed treatments, shoots or seedlings) or in thepreemergence application or post-emergence application of the usefulplant. The safeners and the isoxazolo[5,4-b]pyridines of formula I canbe applied simultaneously or in succession.

Suitable safeners are, for example, (quinolin-8-oxy)acetic acids,1-phenyl-5-haloalkyl-1H-1,2,4-triazole-3-carboxylic acids,1-phenyl-4,5-dihydro-5-alkyl-1H-pyrazole-3,5-dicarboxylic acids,4,5-dihydro-5,5-diary)-3-isoxazolecarboxylic acids, dichloroacetamides,alpha-oximinophenylacetonitriles, acetophenonoximes,4,6-dihalo-2-phenylpyrimidines,N-[[4-(aminocarbonyl)phenyl]sulfonyl]-2-benzamides, 1,8-naphthalicanhydride, 2-halo-4-(haloalkyl)-5-thiazolecarboxylic acids,phosphorothioates, N-alkyl-O-phenylcarbannates and 2-oxo-nicotinamidesand their agriculturally suitable salts, and, assuming that they have anacid function, their agriculturally suitable derivatives such as amides,esters and thioesters.

Hereinbelow, the preparation of representative isoxazolo[5,4-b]pyridinesof formula I is illustrated by examples:

-   -   NMR spectra were recorded on a Bruker Avance II 300. LC-MS were        recorded on a Waters system with the following conditions:

Column: XTerra MS C₁₈ 5 μm (4.6×100 mm)

Gradient: from 95% H₂O/5% MeOH to 100% MeOH in 8 minFlow: 1.5 mL/min

Alternatively, a Shimadzu Nexera UHPLC in combination with Shimadzu LCMS20-20, ESI was used; column: Phenomenex Kinetex 1.7 μm XB-C18 100A;

Synthesis of Compound 1

Na (14.67 g, 0.64 mmol) was dissolved in dry MeOH (0.8 L) and a solutionof cyclopropylmethylketone (50 g, 0.59 mmol) and dimethyloxalate (70.2g, 0.59 mmol) in dry MeOH (0.2 L) was added dropwise at 0° C. Thereaction mixture was stirred at r.t. 24 h and reflux overnight. Water(0.5 L) was added and the methanol was removed under reduced pressure.The aqueous solution was washed with Et₂O (150 mL), acidified to pH=2with 2M H₂SO₄ and extracted with Et₂O (3×150 mL). The organic layer wasdried over MgSO₄ and concentrated to dryness, to yield compound 1 (55.6g, 55%), which was used without further purification.

¹H-NMR (CDCl₃): δ=14.61 (br, 1H), 6.84 (s, 1H), 3.90 (s, 3H), 1.95-1.82(m, 1H), 1.26-1.20 (m, 2H), 1.10-1.00 (m, 2H).

Synthesis of Compound 2

A mixture of compound 1 (0.9 g, 5.3 mmol) and5-amino-3-(2-phenylethyl)isoxazole (1.0 g, 5.3 mmol) in AcOH (16 mL) wasstirred at reflux for 4 h. The reaction mixture was poured intoice/water (100 mL). The solid formed was collected by filtration anddried under high vacuum. 1.5 g (79%) of compound 2 were obtained.

¹H-NMR (CDCl₃): δ=7.62 (s, 1H), 7.27-7.11 (m, 5H), 3.93 (s, 3H),3.43-3.37 (m, 2H) 3.03-2.97 (m, 2H), 2.22-2.10 (m, 1H), 1.24-1.17 (m,2H), 1.13-1.05 (m, 2H).

MS: m/z=323 [M+H]+, 345 [M+Na]+

Synthesis of Compound 3

A solution of compound 2 (1.0 g, 3.1 mmol) in a mixture 1:1 THF/1N NaOH(15 mL) was stirred at r.t. for 2 h. The reaction was concentrated invacuum, the aqueous solution was acidified to pH=2 with 10% HCl andextracted with AcOEt (3×10 mL). The organic layer was dried over MgSO₄and concentrated to dryness. The residue was stirred in petroleum/Et₂O10:1 and the solid obtained was collected by filtration and dried underhigh vacuum to yield compound 3 (0.82 g, 85%).

¹H-NMR (CDCl₃): δ=7.81 (s, 1H), 7.31-7.13 (m, 5H), 3.52-3.46 (m, 2H)3.12-3.05 (m, 2H), 2.34-2.22 (m, 1H), 1.34-1.28 (m, 2H), 1.26-1.17 (m,2H).

MS: m/z=331 [M+Na]+, 353 [M−H+2Na]+, 639 [2M−2H+3Na]+

Synthesis of Compound 4

A mixture of compound 1 (3 g, 17.6 mmol) and 5-amino-3-methylisoxazole(1.73 g, 17.6 mmol) in AcOH (44 mL) was stirred at reflux for 2 h. Thereaction mixture was poured into ice/water (100 mL). The solid formedwas collected by filtration and dried under high vacuum. 3.9 g (97%) ofcompound 4 were obtained.

¹H-NMR (CDCl₃): δ=7.69 (s, 1H), 4.02 (s, 3H), 2.69 (s, 3H), 2.26-2.15(m, 1H), 1.28-1.21 (m, 2H), 1.19-1.11 (m, 2H).

MS: m/z=233 [M+H]+

Synthesis of Compound 5

A solution of compound 4 (2.7 g, 11.6 mmol) in a mixture 1:1 THF/1N NaOH(52 mL) was stirred at r.t. for 1.5 h. The reaction was concentrated invacuum, the aqueous solution was acidified to pH=2 with 10% HCl and thesolid formed was collected by filtration and dried under high vacuum toyield compound 5 (2.4 g, 94%).

¹H-NMR (DMSO-d₆): δ=7.78 (s, 1H), 2.59 (s, 3H), 2.46-2.36 (m, 1H),1.18-1.01 (m, 4H).

MS: m/z=219 [M+H]+.

Synthesis of Compound 6

A mixture of compound 5 (0.7 g, 3.2 mmol) in SOCl₂ (6.4 mL) was refluxedovernight. The volatiles were removed under vacuum using toluene asco-solvent. 760 mg of compound 6 were obtained and used without furtherpurification.

Synthesis of Compound 7

To a solution of compound 6 (0.38 g, 1.6 mmol) in dry dichloromethane (8mL) were added methanosulfonamide (0.17 g, 1.8 mmol) andN,N-Diisopropylethylamine (0.25 g, 1.9 mmol) at 0° C. The mixture wasstirred at r.t. for 12 h. The reaction mixture was poured into aq. 5%citric acid (20 mL) and extracted with dichloromethane (3×10 mL). Theorganic layer was dried over MgSO₄ and concentrated to dryness. Theresidue was stirred in Et₂O and the solid formed was collected byfiltration and after drying it was purified by prep. TLC (SiO₂,CHCl₃/MeOH 95:5). 160 mg (34%) of compound 7 were obtained.

¹H-NMR (CDCl₃): δ=7.36 (s, 1H), 3.37 (s, 3H), 2.57 (s, 3H), 2.22-2.11(m, 1H), 1.25-1.05 (m, 4H).

MS: m/z=347 [M+Na]+, 671 [2M+Na]+.

Synthesis of compound 8

To a solution of N-methoxy-N-methyl cyclopropanecarboxamide (8 g, 62mmol) in dry THF (93 mL) was added dropwise at 78° C. a solution 1Methylmagnesiumbromide in THF (62 mL, 62 mmol) under nitrogen atmosphere.The reaction mixture was slowly allowed to warm up to 0° C., poured intophosphate buffer solution (150 mL, pH=7) and extracted with Et₂O (3×50mL). The organic layer was dried over MgSO₄ and concentrated at 45°C./400 mbar. The residue consisted in a mixture 1:2 compound 8/THF (9.2g, ˜3.7 g product, ˜61%) and it was used without further purification.

¹H-NMR (CDCl₃): δ=2.54 (c, J=7.33 Hz, 2H), 1.94-1.84 (m, 1H), 1.04 (t,J=7.33 Hz, 3H), 1.00-0.92 (m, 2H), 0.85-0.76 (m, 2H).

Synthesis of Compound 9

Na (0.93 g, 40.4 mmol) was dissolved in dry MeOH (52 mL) and a solutionof compound 8 (3.7 g, 37.7 mmol) and dimethyloxalate (4.45 g, 37.7 mol)in dry MeOH (15 mL) was added dropwise at 0° C. The reaction mixture wasstirred at r.t. 18 h. Dimethyloxalate (4.45 g, 37.7 mol) and 30% NaOMein MeOH (7.5 mL) were added and the mixture was stirred at r.t. 18 h.More 30% NaOMe in MeOH (2.5 mL) was added and the mixture was stirred atr.t. 18 h before it was poured into water (200 mL). The methanol wasremoved under reduced pressure. The aqueous solution was washed withEt₂O (25 mL), acidified to pH=2 with 2M H₂SO₄ and extracted with Et₂O(3×50 mL). The organic layer was dried over MgSO₄ and concentrated todryness, to yield compound 9 (5.1 g, ˜82%) which was used withoutfurther purification.

Synthesis of Compound 10

A mixture of compound 9 (5 g, 27.1 mmol) and 5-amino-3-methylisoxazole(2.66 g, 27.1 mmol) in AcOH (78 mL) was stirred at reflux for 1 h. Thereaction mixture was concentrated to dryness and the residue wasdissolved in AcOEt (50 mL) and washed with aq. sat. NaHCO3 (2×15 mL).The organic layer was dried over MgSO₄ and concentrated to dryness. Theresidue was purified by flash column chromatography (SiO₂, c-Hex/AcOEt)to yield compound 10 (1.3 g, 18%).

¹H-NMR (CDCl₃): δ=2.50 (s, 3H), 2.43 (s, 3H), 2.30-2.20 (m, 1H),1.30-1.22 (m, 2H), 1.16-1.07 (m, 2H).

MS: m/z=269 [M+Na]+.

Synthesis of Compound 11

A solution of compound 10 (0.6 g, 2.1 mmol) in a mixture 1:1 THF/1N NaOH(12 mL) was stirred at r.t. for 12 h. The reaction was concentrated invacuum, the aqueous solution was acidified to pH=2 with 10% HCl andextracted with dichloromethane (3×25 mL). The organic layer was driedover MgSO₄ and concentrated to dryness. The residue was stirred inpetroleum ether/Et₂O 10:1 and the solid obtained was collected byfiltration and dried under high vacuum to yield compound 11 (0.41 g,85%).

¹H-NMR (MeOD-d₄): δ=2.44 (s, 3H), 2.38 (s, 3H), 2.32-2.25 (m, 1H),1.10-1.00 (m, 2H).

MS: m/z=233 [M+H]+, 255 [M+Na]+, 277 [M−H+2Na]+.

Synthesis of Compound 12

Na (0.76 g, 33.1 mmol) was dissolved in dry MeOH (42 mL) and a solutionof 3,3,4,4,4-Pentafluoro-butan-2-one (5 g, 30.9 mmol) anddimethyloxalate (3.64 g, 30.9 mmol) in dry MeOH (13 mL) was addeddropwise at 0° C. The reaction mixture was stirred at r.t. overnight.Water (50 mL) was added and the methanol was removed under reducedpressure. The aqueous solution was washed with Et₂O (25 mL), acidifiedto pH=2 with 2M H₂SO₄ and extracted with Et₂O (3×25 mL). The organiclayer was dried over MgSO₄ and concentrated to dryness, to yieldcompound 12 (2 g, 26%) which was used without further purification.

¹H-NMR (CDCl₃): δ=6.28 (s, 1H), 3.92 (s, 3H).

Synthesis of Compound 13

A mixture of compound 12 (2 g, 8.1 mmol) and 5-amino-3-methylisoxazole(0.67 g, 6.8 mmol) in AcOH (20 mL) was stirred at reflux for 1 h. Thereaction mixture was poured into ice/water (50 mL) and extracted withEt₂O (3×25 ml). The organic layer was washed with aq. sat. NaHCO3 (2×15mL), dried over MgSO₄ and concentrated to dryness. The reaction crudewas purified by flash column chromatography (SiO₂, c-Hex/AcOEt) to give60 mg of compound 13 (2.4%).

Synthesis of Compound 14

A solution of compound 13 (56 mg, 0.2 mmol) in a mixture 1:1 THF/1N NaOH(2 mL) was stirred at r.t. for 4 h. The reaction was concentrated invacuum, the aqueous solution was acidified to pH=2 with 10% HCl andextracted with dichloromethane (3×5 mL). The organic layer was driedover MgSO₄ and concentrated to dryness. The residue was stirred inpetroleum ether/Et₂O 10:1 and the solid obtained was collected byfiltration and dried under high vacuum to yield compound 14 (44 mg,88%).

¹H-NMR (CDCl₃): δ=8.31 (s, 1H), 2.86 (s, 3H).

MS: m/z=319 [M+Na]+, 341 [M−H+2Na]+

Synthesis of Compound 16

A mixture of compound 15 (0.85 g, 3.9 mmol) and p-toluenesulfonic acid(0.27 g, 1.5 mmol) in MeOH (17 mL) was refluxed for 4 days. The solventwas removed and the residue was diluted with a mixture CHCl₃/2-propanol7:3 (50 mL) and washed with aq. sat. NaHCO3 (2×15 mL). The organic layerwas dried over MgSO₄ and concentrated to dryness. 620 mg (69%) ofcompound 16 were obtained and used without further purification.

¹H-NMR (CDCl₃): δ=7.19 (s, 1H), 4.04 (s, 3H), 2.59-2.44 (m, 1H),1.25-1.17 (m, 2H), 1.15-1.00 (m, 2H).

MS: m/z=335 [M+H]+, 357 [M+Na]+

Synthesis of Compound 17

To a solution of compound 16 (0.19 g, 0.8 mmol) in dry dichloromethane(3 mL) were added at 0° C. pyridine (80 mg, 1 mmol) andtrifluoromethanosulfonic anhydride (0.29 g, 1 mmol) and the mixture wasstirred at this temperature for ½ h and at r.t. for 8 h. The reactionwas diluted with water (3 mL) and extracted with DCM (2×5 mL). Theorganic layer was dried over MgSO₄ and concentrated to dryness. Thereaction crude was purified by flash column chromatography to give 190mg (63%) of compound 17.

¹H-NMR (CDCl₃): δ=7.66 (s, 1H), 4.07 (s, 3H), 2.71-2.57 (m, 1H),1.22-1.10 (m, 4H).

MS: m/z=367 [M+H]+.

Synthesis of Compound 18

A mixture of compound 17 (150 mg, 0.41 mmol), LiCl (90 mg, 2.1 mmol),tributylvinyltin (170 mg, 0.53 mmol) andbis(triphenylphosphine)palladium (II) dichloride (50 mg, 0.07 mmol) indry DMF (5 mL) was stirred at 80° C. for 1 h. After cooling down, asolution of NaF (390 mg) in water (4.5 mL) was added and the mixture wasstirred at r.t. for 1 h. The reaction mixture was filtered through acelite-pad and the filter-cake was washed with AcOEt. The layers of thefiltrate were separated, the aqueous layer was extracted with AcOEt(3×10 mL) and the combined organic layer was dried over MgSO₄ andconcentrated to dryness. The reaction crude was purified by flash columnchromatography to give 80 mg (80%) of compound 18. The compound soobtained presented some impurities from tin-reagent.

¹H-NMR (CDCl₃): δ=7.81 (s, 1H), 6.92 (dd, J=17.4, 10.7 Hz, 1H), 6.51 (d,J=17.4 Hz, 1H), 5.73 (d, J=10.7 Hz, 1H), 4.04 (s, 3H), 2.67-2.57 (m,1H), 1.20-1.14 (m, 2H), 1.13-1.05 (m, 2H).

MS: m/z=467 [M+Na]+.

Synthesis of Compound 19

To a solution of compound 18 (100 mg, 0.41 mmol) in dichloromethane (4mL) was added at 0° C. a solution of meta-chloroperoxybenzoic acid (71mg, 0.41 mmol) in dichloromethane (4 mL), which was previously driedover MgSO₄. The reaction mixture was stirred at r.t 24 h, before a newsolution of meta-chloroperoxybenzoic acid (71 mg, 0.41 mmol) indichloromethane (4 mL) was added. This operation was repeated twice. Themixture was washed with aq. sat. NaHCO3 (3×10 mL) and the organic layerwas dried over MgSO₄ and concentrated to dryness. The residue waspurified by prep. TLC (SiO₂, c-Hex/AcOEt), to give 45 mg (41%) ofcompound 19. The compound 19 so obtained contained somemeta-chlorobenzoic acid.

¹H-NMR (CDCl₃): δ=7.69 (s, 1H), 4.19-4.14 (m, 1H), 4.03 (s, 3H), 3.29(dd, J=5.1, 4.1 Hz, 1H), 3.01 (dd, J=5.3, 2.1 Hz, 1H), 2.70-2.57 (m,1H), 1.20-1.14 (m, 2H), 1.14-1.07 (m, 2H).

Synthesis of Compound 20

A mixture of compound 1 (17 g, 0.1 mol) and 5-amino-isoxazol-3-one (10g, 0.1 mol) in acetic acid (AcOH) (100 mL) was stirred at reflux for 2h. The reaction mixture was poured into ice/water (200 mL). The solidformed was collected by filtration and dried under high vacuum. 19 g(82%) of compound 20 were obtained.

¹H-NMR (CDCl₃): δ=10.30 (bs, 1H), 7.69 (s, 1H), 4.12 (s, 3H), 2.27-2.20(m, 1H), 1.29-1.22 (m, 2H), 1.21-1.12 (m, 2H).

MS: m/z=235 [M+H]+

Synthesis of Compound 21

To a stirred solution of triphenylphosphine (12.3 g, 46.9 mmol) in dryTHF (150 mL) was added dropwise diisopropyl azodicarboxylate (9.5 g,46.9 mmol) at 0° C. under nitrogen atmosphere, and the mixture wasstirred for 20 min. Then, t-BuOH (3.5 g, 47.2 mmol) and compound 20 (10g, 42.7 mmol) were added at 0° C. The mixture was stirred at r.t. for 2h and heated to 40° C., stirred overnight. The mixture was cooled to r.tand another portion of triphenylphosphine (12.3 g, 46.9 mmol), t-BuOH(3.5 g, 47.2 mmol) and diisopropyl azodicarboxylate (9.5 g, 46.9 mmol)were added. The mixture was stirred at r.t. for 1 h and heated to 60°C., stirred overnight. The solvent was removed under reduced pressure.The residue was purified by column chromatography (SiO₂, c-Hex/AcOEt) togive compound 21 (5.6 g, yield: 45%)

¹H-NMR (CDCl₃): δ=7.52 (s, 1H), 4.00 (s, 3H), 2.25-2.16 (m, 1H), 1.65(s, 9H), 1.28-1.21 (m, 2H), 1.19-1.11 (m, 2H).

MS: m/z=235 [M−tBu+H]+

Synthesis of Compound 22

A mixture of compound 20 (12 g, 0.05 mmol), pyridine hydrochloride (20g, 0.17 mol), H₃PO₄ (3.6 g, 0.04 mmol) and POCl₃ (120 mL) was stirred at90° C. for 3 h. The excess of POCl₃ was evaporated under high vacuum.Remaining mixture was dissolved in ethyl acetate and slowly neutralizedwith NaHCO3 at 0° C. The organic layer was washed with brine and water,dried over MgSO₄ and concentrated to dryness. The residue was purifiedby column chromatography (SiO₂, c-Hex/AcOEt) to give compound 22 (6.5 g,yield: 50%).

¹H-NMR (CDCl₃): δ=7.72 (s, 1H), 4.05 (s, 3H), 2.29-2.20 (m, 1H),1.32-1.26 (m, 2H), 1.25-1.18 (m, 2H).

MS: m/z=253 [M+H]+

Synthesis of Compound 24

To the solution of hydroxy-acetic acid ethyl ester 23 (99.6 g, 0.96mmol) in THF (1.5 L) under nitrogen atmosphere, NaH (42 g, 1.0 mol: 60%in mineral oil) was added at 0° C. in portions. The mixture was stirredat 0° C. for 30 min and tetrabutylammonium iodide (35.3 g, 0.10 mol) andbenzyl bromide (163.6 g, 0.96 mmol) were added. The mixture was allowedto warm up to r.t and was stirred in this temperature for 12 h. Thereaction mixture was diluted with water and extracted with ethylacetate. The organic layer was dried over MgSO₄, solvent was evaporatedunder high vacuum and raw product was destilled (121° C./4 mBar) to givecompound 24 (135.5 g, yield: 73%).

¹H-NMR (CDCl₃): δ=7.41-7.22 (m, 5H), 4.65 (s, 2H), 4.27 (q, 2H), 4.11(s, 2H), 1.25 (t, 3H).

Synthesis of Compound 25

Tetrahydrofuran (1 L) and NaH (30 g, 0.77 mol: 60% in mineral oil) werestirred under nitrogen atmosphere and heated to 50° C. To this mixture,a tertahydrofuran solution of compound 24 (135.5 g, 0.70 mol) andacetonitrile (37.1 g, 0.90 mol) were added. The reaction was stirred atr.t. for 12 h. The reaction mixture was diluted with water and extractedwith MTBE (Methyl tert-butyl ether). The water phase was acidified withcitric acid (pH=3) and extracted with ethyl acetate. The organic layerwas washed with brine and water, dried over MgSO₄ and concentrated todryness. The residue was purified by column chromatography (SiO₂,c-Hex/AcOEt) to give compound 25 (41 g, yield: 31%)

¹H-NMR (CDCl₃): δ=7.40-7.21 (m, 5H), 4.58 (s, 2H), 4.10 (s, 2H), 3.61(s, 2H).

Synthesis of Compound 26

A mixture of compound 25 (63.3 g, 0.33 mmol), hydroxylaminehydrochloride (30.2 g, 0.43 mmol) and sodium acetate (82.3 g, 1 mol) inEtOH (1 L) was stirred at r.t. for 4 h. Solvent was removed under highvacuum. The reaction mixture was poured into water and extracted withmethylene chloride. The organic layer was washed with brine and water,dried over MgSO₄ and concentrated to dryness. The residue was purifiedby column chromatography (SiO₂, c-Hex/AcOEt) to give compound 26 (13.8g, yield: 20%).

¹H-NMR (CDCl₃): δ=7.40-7.22 (m, 5H), 5.20 (s, 1H), 4.55 (bs, 4H), 4.46(s, 2H).

Synthesis of Compound 27

A mixture of compound 1 (11.5 g, 0.07 mol) and 26 (13.8 g, 0.07 mol) inAcOH (150 mL) was stirred at reflux for 2 h. The reaction mixture waspoured into ice/water (200 mL). The solid formed was collected byfiltration and dried under high vacuum. 16.5 g (72%) of compound 27 wereobtained.

¹H-NMR (CDCl₃): δ=7.68 (s, 1H), 7.32 (s, 5H), 5.03 (s, 2H), 4.60 (s,2H), 3.95 (s, 3H), 2.26-2.20 (m, 1H), 1.30-1.25 (m, 2H), 1.20-1.12 (m,2H).

MS: m/z=339 [M+H]+

Synthesis of Compound 28

BCl₃ (5.9 mL, 5.91 mmol; 1M in CH₂Cl₂) was slowly added to a solution ofcompound 27 (1 g, 2.96 mmol) in CH₂Cl₂ (20 mL) at −78° C. and thereaction mixture was stirred at this temperature for 2 h. Saturatedaqueous NaHCO3 was added. The layers were separated and the organiclayer was washed with brine and water, dried over MgSO₄ and concentratedto dryness. The residue was stirred with diisopropylether and the solidformed was collected by filtration and dried under high vacuum to givecompound 29 (0.5 g, yield: 68%).

¹H-NMR (CDCl₃): δ=7.80 (s, 1H), 5.00 (s, 2H), 4.07 (s, 3H), 3.88 (bs,1H), 2.28-2.20 (m, 1H), 1.30-1.25 (m, 2H), 1.20-1.15 (m, 2H).

The isoxazolo[5,4-b]pyridines according to tables 7 to 14 below wereprepared in accordance with the methods described above; compoundslabeled “(−)” are not part of the present invention:

TABLE 7 compounds labeled “(-)” are not part of the present invention(I.1)

cpd.-no X R.T. (min) m/z = [M + H]+ I.1.1 (-)

3.241 370.1 I.1.2 (-)

3.082 401.1 I.1.3

2.781 345.1 I.1.4 (-)

3.527 385.1 I.1.5

3.541 477.1 I.1.6 OCH₂CN 3.147 258.1 I.1.7

3.734 426.2 I.1.8 (-)

2.892 409.1 I.1.9 (-)

3.943 383.1 I.1.10

3.943 383.1 I.1.11

4.283 361.1 I.1.12 (-)

3.741 406.2 I.1.13 (-)

3.646 384.1 I.1.14

4.106 353.1 I.1.15

3.899 366.1 I.1.16 (-)

3.473 410.1 I.1.17

3.941 381.1 I.1.18 (-)

3.490 324.1 I.1.19 (-)

3.604 366.1 I.1.20

3.477 483.1 I.1.21 (-)

3.794 350.1 I.1.22 (-)

3.530 380.1 I.1.23 (-)

3.491 422.2 I.1.24

2.600 290.1 I.1.25 (-)

3.847 386.2 I.1.26 (-)

3.346 391.1 I.1.27 (-)

3.927 437.1 I.1.28 (-)

2.883 422.1 I.1.29 (-)

2.978 330.1 I.1.30 (-)

4.140 395.1 I.1.31 (-)

4.043 406.1 I.1.32 (-)

4.057 434.2 I.1.33 (-)

3.875 436.2 I.1.34

3.686 344.1 I.1.35

3.804 372.2 I.1.36

4.082 388.2 I.1.37

4.156 417.1 I.1.38 (-)

3.503 386.1 I.1.39 OCH₃ 3.254 233.1 I.1.40

4.099 398.0 I.1.41 (-)

3.984 406.2 I.1.42 (-)

3.437 386.1 I.1.43 (CH₃)₃COCOCH₂O 3.989 333.1 I.1.44 (-)

3.624 396.1 I.1.45 (-)

3.778 424.2 I.1.46 (-)

3.813 414.1 I.1.47 (-)

4.073 405.1 I.1.48 (-)

3.636 358.2 I.1.49

4.063 371.1 I.1.50 (-)

3.653 412.2 I.1.51

3.767 357.1 I.1.52 (-)

3.990 386.2 I.1.53 OCH₂CO₂CH₃ 3.275 291.1 I.1.54 (-)

3.048 384.2 I.1.55 (-)

3.740 373.1 I.1.56

4.007 369.1 I.1.57 (-)

4.196 401.0 I.1.58 (-)

3.641 398.1 I.1.59

4.288 361.1 I.1.60

3.909 391.1 I.1.61 OCH₂OCH₃ 2.592 219.1 I.1.62 OCH₂CH═CH₂ 3.750 259.1I.1.63 OCH₂CH₃ 3.609 247.1 I.1.64 OCH₂CH═CClCH₃ (Z-isomer) 4.170 219.1I.1.65 OCH₂CHF₂ 3.539 283.1 I.1.66 OCH₂CHC(CH₃)₂ 4.234 219.1 I.1.67OCH₂CF₃ 3.824 301.1 I.1.68 OCH₂CCCH₃ 3.761 271.1 I.1.69 O(CH₂)₂OCH₂CH₃3.579 291.1 I.1.70 O[(CH₂)₂O]₂C₄H₉ 4.082 363.2 I.1.71 OC(CH₃)₂ 4.148219.1 I.1.72 OC₃H₇ 3.936 261.1 I.1.73 OCH₂C(CH₃)₂ 4.431 289.1 I.1.74O(CH₂)₂OH 2.641 263.1 I.1.75 O(CH₂)₂OCH═CH₂ 3.705 289.1 I.1.76OCH₂CH═CHC≡CH 3.799 283.1 I.1.77 NHSO₂CH₃ 0.909 296   I.1.78 NHSO₂C₆H₅1.102 358   I.1.79 SCH₂C₆H₅ 1.441 325   I.1.80 SCH₂CHCH₂ 1.351 275  I.1.81 S(CH₂)₃CH₃ 1.480 291   I.1.82 SCH₃ 1.236 249   I.1.83 N(OCH₃)CH₃0.985 262  

TABLE 8 (I.2)

R.T. m/z = cpd.-no R³ (min) [M + H]+ I.2.1 CH₃ 2.574 219.1 I.2.2CH₂C(CH₃)₂ 3.429 275.1 I.2.3 (CH₂)₂CH₃ 3.078 247.1 I.2.4

2.885 271.0 I.2.5 C₆H₅ 3.108 281.1 I.2.6 CH(CH₃)₂ 3.048 247.1 I.2.7

2.920 245.1 I.2.8 4-CH₃O—C₆H₄ 3.176 311.1 I.2.9

2.651 313.1 I.2.10 CF₃ 3.176 273.0 I.2.11 (CH₂)₂C₆H₅ 3.543 309.1 I.2.12

3.180 259.1 I.2.13

3.156 259.1 I.2.14

3.370 273.1 I.2.15

2.078 282.1 I.2.16

0.763 282   I.2.17 4-Cl—C₆H₄ 1.175 315   I.2.18 4-CF₃—C₆H₄ 1.234 349  I.2.19 4-C₆H₅—C₆H₄ 1.287 357   I.2.20 4-Br—C₆H₄ 1.194 360   I.2.213-CF₃—C₆H₄ 1.228 349   I.2.22 3-OCH₃—C₆H₄ 1.110 311   I.2.233-OCH₃,4-OCH₃—C₆H₃ 1.066 341   I.2.24 3-Cl—C₆H₄ 1.183 315   I.2.25CH₂CH₃ 1.012 233   I.2.26

1.218 287   I.2.27

1.232 287   I.2.28 (CH₂)₄CH₃ 1.225 275   I.2.29

1.280 301   I.2.30

1.363 315   I.2.31 3-F—C₆H₄ 1.131 299   I.2.32 3-Cl,5-Cl—C₆H₃ 1.281 349[M]+ I.2.33 2-OCH₃—C₆H₄ 1.090 311   I.2.34 2-OCH₃,3-OCH₃, 1.107 371  4-OCH₃—C₆H₂ I.2.35 2-Cl—C₆H₄ 1.144 315   I.2.36 3-OCH₃,5-OCH₃—C₆H₃ 1.133341   I.2.37 (CH₂)₃C₆H₄ 1.256 323   I.2.38 CH₂OCH₃ 0.938 249   I.2.39(CH₂)₂CH(CH₃)₂ 1.218 275   I.2.40

1.238 329   I.2.41

1.304 313   I.2.42 (CH₂)₂-4-OCH₃—C₆H₄ 1.209 339   I.2.43 4-I—C₆H₄ 1.230406 [M]+ I.2.44 3-F,5-F—C₆H₃ 1.178 317   I.2.45 4-OCHF₂—C₆H₄ 1.170 347  I.2.46

1.058 263   I.2.47

1.146 299   I.2.48 H 0.558 205   I.2.49 CH₂OH 0.825 235   I.2.502-F—C₆H₄ 1.126 299   I.2.51 4-F—C₆H₄ 1.123 299   I.2.52 2-CH₃—C₆H₄ 1.145295   I.2.53 OCH₃ 0.933 235   I.2.54 OCH₂CH₃ 1.004 249   I.2.55O(CH₂)₂CH₃ 1.084 263   I.2.56 O(CH₂)₃CH₃ 1.157 277   I.2.57 OCH(CH₃)₂1.075 263   I.2.58 OC(CH₃)₃ 1.142 277   I.2.59 2-Br—C₆H₄ 1.173 360  I.2.60 2-CF₃—C₆H₄ 1.245 349   I.2.61 4-CH₂CH₃—C₆H₄ 1.232 309   I.2.624-OCH₂CH₃—C₆H₄ 1.187 325   I.2.63 4-O(CH₂)₃CH₃—C₆H₄ 1.313 353   I.2.642-OCHF₂—C₆H₄ 1.152 347   I.2.65 4-NO₂—C₆H₄ 1.164 326   I.2.664-CH(CH₃)₂—C₆H₄ 1.279 323   I.2.67

1.107 285   I.2.68

1.125 285   I.2.69

1.148 301   I.2.70

1.168 301   I.2.71 4-C(CH₃)₃—C₆H₄ 1.333 337   I.2.72 OH 0.884 221  I.2.73

1.103 366   I.2.74 OCH(CH₂CH₃)₂ 1.237 291  

TABLE 9 (I.3)

R.T. m/z = cpd.-no R¹ X (min) [M + H]+ I.3.1 CH₂C₆H₅ OH 3.353 309.1I.3.2 CH₃ OH 2.539 233.1 I.3.3 Br OH 2.606 297.0 I.3.4 Cl OH 2.568 253.0I.3.5 CH₂C₆H₅ OC(CH₃)₃ 4.538 365.2 I.3.6 CH₃ OCH₃ 3.380 247.1 I.3.7 BrOCH₃ 3.770 311.0 I.3.8 Cl OCH₃ 3.732 267.0

TABLE 10 (I.4)

m/z = cpd.- R.T. [M + no R³ X (min) H]+ I.4.1

OCH₃ 4.134 287.1 I.4.2

OCH₃ 2.393 296.1 I.4.3

OCH₃ 3.897 273.1 I.4.4

OCH₃ 3.942 273.1 I.4.5 (CH₂)₂C₆H₅ OCH₃ 4.164 323.1 I.4.6 CF₃ OCH₃ 3.821287.0 I.4.7 4-CH₃O—C₆H₄ OCH₃ 3.820 325.1 I.4.8 4-CH₃—C₆H₄ OCH₃ 4.055309.1 I.4.9 4-F—C₆H₄ OCH₃ 3.882 313.1 I.4.10

OCH₃ 3.287 327.1 I.4.11 2-F—C₆H₄ OCH₃ 3.880 313.1 I.4.12

OCH₃ 3.085 327.1 I.4.13

OCH₃ 0.880 296   I.4.14 4-Cl—C₆H₄ OCH₃ 1.363 329   I.4.15 4-CF₃—C₆H₄OCH₃ 1.390 363   I.4.16 4-C₆H₅—C₆H₄ OCH₃ 1.455 371   I.4.17 4-Br—C₆H₄OCH₃ 1.377 374   I.4.18 3-CF₃—C₆H₄ OCH₃ 1.390 363   I.4.19 3-OCH₃—C₆H₄OCH₃ 1.288 325   I.4.20 3-OCH₃,4-OCH₃—C₆H₃ OCH₃ 1.221 355   I.4.213-Cl—C₆H₄ OCH₃ 1.371 329   I.4.22 CH₂CH₃ OCH₃ 1.214 247   I.4.23

OCH₃ 1.443 301   I.4.24

OCH₃ 1.442 301   I.4.25 (CH₂)₄CH₃ OCH₃ 1.441 289   I.4.26

OCH₃ 1.502 315   I.4.27

OCH₃ 1.567 329   I.4.28 3-F—C₆H₄ OCH₃ 1.306 313   I.4.29 3-Cl,5-Cl—C₆H₃OCH₃ 1.466 363   I.4.30 2-OCH₃—C₆H₄ OCH₃ 1.281 325   I.4.312-OCH₃,3-OCH₃, OCH₃ 1.276 385   4-OCH₃—C₆H₂ I.4.32 2-Cl—C₆H₄ OCH₃ 1.331329   I.4.33 3-OCH₃,5-OCH₃—C₆H₃ OCH₃ 1.305 355   I.4.34 (CH₂)₃C₆H₄ OCH₃1.440 337   I.4.35 CH₂OCH₃ OCH₃ 1.115 263   I.4.36 (CH₂)₂CH(CH₃)₂ OCH₃1.437 289   I.4.37

OCH₃ 1.416 343   I.4.38

OCH₃ 1.517 327   I.4.39 (CH₂)₂-4-OCH₃—C₆H₄ OCH₃ 1.380 353   I.4.404-I—C₆H₄ OCH₃ 1.412 421   I.4.41 3-F,5-F—C₆H₃ OCH₃ 1.178 317   I.4.424-OCHF₂—C₆H₄ OCH₃ 1.327 361   I.4.43

OCH₃ 1.247 277   I.4.44

OCH₃ 1.319 313   I.4.45 CH₂C(CH₃)₃ SCH₃ 1.487 305   I.4.46 2-F—C₆H₄ SCH₃1.369 329   I.4.47 4-F—C₆H₄ SCH₃ 1.375 329   I.4.48 2-CH₃—C₆H₄ SCH₃1.398 325   I.4.49 OC(CH₃)₃ NH₂ 1.175 276   I.4.50 OC(CH₃)₃ SCH₃ 1.320307   I.4.51 OCH(CH₃)₂ NH₂ 1.065 262   I.4.52 OCH(CH₃)₂ SCH₃ 1.378 293  I.4.53 OCH(CH₃)₂ SCH₂C₆H₅ 1.533 369   I.4.54 4-OCH₂CH₃—C₆H₄ SCH₃ 1.421355   I.4.55 4-O(CH₂)₃CH₃—C₆H₄ SCH₃ 1.538 383   I.4.56 2-OCHF₂—C₆H₄ SCH₃1.362 377   I.4.57 4-NO₂—C₆H₄ SCH₃ 1.365 356   I.4.58 NHCH(CH₃)₂CONHCH(CH₃)₂ 1.258 303   I.4.59 (CH₂)₂CH₃ SCH₃ 1.390 277   I.4.60

SCH₃ 1.338 275   I.4.61 2-Br—C₆H₄ SCH₃ 1.416 390   I.4.62 2-CF₃—C₆H₄SCH₃ 1.463 379   I.4.63

NH₂ 0.918 244   I.4.64 OCOC(CH₃)₃ OCH₃ 1.402 319  

TABLE 11 compounds labeled “(−)” are not part of the present invention(I.5)

R.T. m/z = cpd.-no R² (min) [M + H]+ I.5.1 (−) 2-CF₃—C₆H₄ 3.539 323.0I.5.2 CH₃ 1.941 193.0 I.5.3 CH(CH₃)₂ 2.693 221.1 I.5.4 CH₂CH₃ 2.330207.1 I.5.5 (−) 2-F—C₆H₄ 3.052 273.0 I.5.6 (−) 4-F—C₆H₄ 3.167 273.0I.5.7

2.610 244.0 I.5.8 (−) 2-CH₃—C₆H₄ 3.314 269.1 I.5.9

3.186 258.0 I.5.10

3.280 272.1 I.5.11 (−) 4-CH₃O—C₆H₄ 3.065 285.1 I.5.12

1.575 256.1 I.5.13 (−) 4-CHF₂O—C₆H₄ 3.306 321.0 I.5.14

2.545 273.1 I.5.15

3.005 233.1 I.5.16 (−) 4-NO₂—C₆H₄ 3.125 300.1 I.5.17 (−)

3.015 299.0 I.5.18 CH₂CH(CH₃)₂ 2.960 235.1 I.5.19 (CH₂)₄CH₃ 3.347 249.1I.5.20

2.867 233.0 I.5.21

3.387 261.1 I.5.22

3.142 247.1 I.5.23 CH₂C₆H₅ 3.009 269.1 I.5.24 CF₂CF₃ 3.195 297.0 I.5.25

2.919 233.1 I.5.26 CH₂C(CH₃)₂OCH₃ 2.484 233.1 I.5.27 C(CH₃)₃ 3.069 235.1I.5.28 (−) 3-Cl—C₆H₄ 3.469 289.0 I.5.29 (−) 2-Cl—C₆H₄ 3.116 289.0 I.5.30(−) 4-C₂H₅O—C₆H₄ 3.358 299.1 I.5.31 (−) 2-CH₃,4-CH₃—C₆H₃ 3.409 283.1I.5.32 (−) 2-F,5-F—C₆H₃ 3.223 291.0 I.5.33 (−) 4-CH₃O—C₆H₄ 2.990 285.1I.5.34 CF₃ 0.938 247  

TABLE 12 (I.6)

m/z = cpd.-no R² X R.T. (min) [M + H]+ I.6.1 CH₂C(CH₃)₂OCH₃ OCH₃ 2.041270.1 I.6.2 C₆H₅ OCH₃ 3.140 247.1 I.6.3

OCH₃ 3.624 247.1 I.6.4 CH₂C₆H₅ OCH₃ 3.617 283.1 I.6.5

OCH₃ 3.860 261.1 I.6.6

OCH₃ 4.114 275.1 I.6.7

OCH₃ 3.585 247.1 I.6.8 (CH₂)₄CH₃ OCH₃ 4.044 263.1 I.6.9 CH₂CH(CH₃)₂ OCH₃3.664 249.1 I.6.10

OCH₃ 3.712 247.1 I.6.11 C(CH₃)₃ OCH₃ 3.770 249.1 I.6.12 CH₃ OCH₃ 2.643207.1 I.6.13

OCH₃ 3.216 287.1 I.6.14 CH₃ OCH(CH₃)CONH₂ 2.082 264.1 I.6.15 CH₃

2.855 300.1 I.6.16 CH(CH₃)₂ OCH₃ 3.427 235.1

TABLE 13 compounds labeled “(−)” are not part of the present invention(I.7)

cpd.-no R² R³ X R.T. (min) m/z = [M + H]+ I.7.1 (−) 3,4-CH₃O—C₆H₃CH(CH₃)₂ OH 3.193 343.1 I.7.2

CH(CH₃)₂ OCH₃ 4.481 337.0 I.7.3 (−) 4-CH₃O—C₆H₄ CH(CH₃)₂ OH 3.450 313.1I.7.4 (−) 4-F—C₆H₄ CH(CH₃)₂ OH 3.561 301.1 I.7.5 (−) 2-CH₃O,5-CH₃O—C₆H₃CH(CH₃)₂ OH 3.379 343.1 I.7.6 (−) 2-CH₃O,4-CH₃O—C₆H₃ CH(CH₃)₂ OH 3.422343.1 I.7.7 (−) 2-CH₃O—C₆H₄ CH(CH₃)₂ OH 3.390 313.1 I.7.8

CH(CH₃)₂ OH 3.360 247.0 I.7.9 (−) 4-Cl—C₆H₄ CH(CH₃)₂ OH 3.886 275.0I.7.10 CH₃ CH(CH₃)₂ OH 2.459 221.1 I.7.11

CH(CH₃)₂ OH 1.969 284.1 I.7.12

OH 2.936 271.1 I.7.13 CH₃

OH 2.323 219.1 I.7.14 (−) C₆H₅

OH 3.371 281.1 I.7.15 (−) 2-F—C₆H₄

OH 3.374 299.1 I.7.16 (−) 4-F—C₆H₄

OH 3.480 299.1 I.7.17 CH₂CH₃

OH 2.710 233.1 I.7.18 (−) 3-Cl,4-Cl—C₆H₃ C₆H₅ OH 4.190 385.0 I.7.19 (−)3-NO₂—C₆H₄ C₆H₅ OH 4.122 376.1 I.7.20 (−) 4-CH₃—C₆H₄ C₆H₅ OH 3.750 331.1I.7.21 (−) 3-CHF₂O—C₆H₄ C₆H₅ OH 3.679 383.1 I.7.22 (−) 2-F—C₆H₄ C₆H₅ OH3.513 335.1 I.7.23 (−) 4-CHF₂O—C₆H₄ C₆H₅ OH 3.681 383.1 I.7.24 (−) C₆H₅C₆H₅ OH 3.520 317.0 I.7.25 (−)

C₆H₅ OH 3.455 361.1 I.7.26 (−) 2-Cl,4-Cl—C₆H₃ C₆H₅ OH 3.927 385.0 I.7.27CH(CH₃)₃ C₆H₅ OH 3.240 283.1 I.7.28

C₆H₅ OH 2.818 335.1 I.7.29

C₆H₅ OH 2.107 318.1 I.7.30

C₆H₅ OH 3.114 307.1 I.7.31 CH₃ C₆H₅ OH 2.585 255.1 I.7.32 (−) C₆H₅

OH 3.295 307.0 I.7.33 (−) 4-CH₃O—C₆H₄

OCH₃ 3.916 351.1 I.7.34 (−) 4-F—C₆H₄

OH 3.398 325.0 I.7.35 (−) 2-CH₃O—C₆H₄

OH 3.249 337.1 I.7.36 (−) 2-CH₃O,4-CH₃O—C₆H₃

OH 3.312 367.1 I.7.37

OH 2.904 297.6 I.7.38 CH₃

OH 2.298 245.0 I.7.39 CH₃ (CH₂)₂CH₃ OH 2.514 221.1 I.7.40

(CH₂)₂CH₃ OH 3.119 231.0 I.7.41 CH₃ CH₂C(CH₃)₃ OH 2.933 249.1 I.7.42C₆H₅ 2-F—C₆H₄ OH 3.606 335.1 I.7.43 C₆H₅ 4-F—C₆H₄ OH 3.605 335.1 I.7.44C₂H₅

OH 2.465 301.1 I.7.45 CH₃

OH 2.147 287.1 I.7.46 (−) CH₃

OCH₃ 3.270 313.1 I.7.47 CH(CH₃)₂ 3-CH₃O—C₆H₄ OH 3.312 313.1 I.7.48 CH₃3-CH₃O—C₆H₄ OH 2.699 285.1 I.7.49 CH₃ 4-CH₃O—C₆H₄ OH 2.700 285.1 I.7.50CH₃

OH 2.297 287.1 I.7.51

CH₃ OH 0.998 237   I.7.52

OH 1.097 263   I.7.53

OCH₃ 1.290 277   I.7.54

OCH₃ 1.283 295   I.7.55

OH 1.069 281   I.7.56

C₆H₅ OH 1.119 317   I.7.57

4-OCH₃—C₆H₄ OH 1.128 347   I.7.58

CH₃ OH 0.985 256   I.7.59

4-CF₃—C₆H₄ OH 1.281 367   I.7.60

4-Br—C₆H₄ OH 1.251 378   I.7.61

4-OCH₃—C₆H₄ OH 1.165 329   I.7.62

C₆H₅ OH 1.155 299   I.7.63

(CH₂)₂CH₃ OH 1.158 265   I.7.64

C(CH₃)₃ OH 1.180 279   I.7.65

4-OCHF₂—C₆H₄ OH 1.222 365   I.7.66

(CH₂)₃CH₃ OH 1.228 279   I.7.67

CH(CH₃)₂ OH 1.155 265   I.7.68

CH₂CH(CH₃)₂ OH 1.218 279   I.7.69

CH₂C(CH₃)₃ OH 1.263 293   I.7.70

(CH₂)₂C₆H₅ OH 1.283 327   I.7.71

OH 1.300 305   I.7.72

OH 1.243 291   I.7.73

CH(CH₃)(CH₂)₂CH₃ OH 1.284 293   I.7.74

SCH₃ 1.401 293   I.7.75

OH 1.198 277   I.7.76

CH₂C₆H₅ OH 1.226 313   I.7.77

(CH₂)₂CH(CH₃)₂ OH 1.295 293   I.7.78

4-OCH₂CH₃—C₆H₄ OH 1.234 343   I.7.79

OH 1.185 277   I.7.80

C(CH₃)₂CH₂CH₃ OH 1.239 293   I.7.81

3-F,4-Br—C₆H₃ OH 1.300 396   I.7.82

OH 1.198 277   I.7.83

3-F,4-F—C₆H₃ OH 1.230 335   I.7.84

OCH(CH₃)₂ NH₂ 1.103 280   I.7.85

OCH(CH₃)₂ OH 1.152 281   I.7.86

OCH(CH₃)₂ SCH₃ 1.431 311   I.7.87

OCH(CH₃)₂ SCH₂C₆H₅ 1.573 387   I.7.88

OCH(CH₃)₂ SC(CH₃)₃ 1.593 353   I.7.89

OCH(CH₃)₂ OCH₂OCH₃ 1.160 281 [M − CH₂OCH₃ + H]+ I.7.90

CH₂CH₃ OH 3.002 251  

TABLE 14 m/z = cpd.-no R.T. (min) [M + H]+ I.8.1

2.119 219.1 1.8.2

3.12 324.1 1.8.3

2.93 261.0 1.8.4

3.60 259.1 1.8.5

3.37 323.0 1.8.6

3.44 257.1

Use Examples

The herbicidal activity of the isoxazolo[5,4-b]pyridines of formula Iwas demonstrated by the following greenhouse experiments:

The culture containers used were plastic flowerpots containing loamysand with approximately 3.0% of humus as the substrate. The seeds of thetest plants were sown separately for each species.

For the pre-emergence treatment, the active ingredients, which had beensuspended or emulsified in water, were applied directly after sowing bymeans of finely distributing nozzles. The containers were irrigatedgently to promote germination and growth and subsequently covered withtransparent plastic hoods until the plants had rooted. This cover causeduniform germination of the test plants, unless this has been impaired bythe active ingredients.

For the post-emergence treatment, the test plants were first grown to aheight of 3 to 15 cm, depending on the plant habit, and only thentreated with the active ingredients which had been suspended oremulsified in water. For this purpose, the test plants were either sowndirectly and grown in the same containers, or they were first grownseparately as seedlings and transplanted into the test containers a fewdays prior to treatment.

Depending on the species, the plants were kept at 10-25° C. or 20-35° C.The test period extended over 2 to 4 weeks. During this time, the plantswere tended, and their response to the individual treatments wasevaluated.

Evaluation was carried out using a scale from 0 to 100. 100 means noemergence of the plants, or complete destruction of at least the aerialmoieties, and 0 means no damage, or normal course of growth. A goodherbicidal activity is given at values of at least 80 and a very goodherbicidal activity is given at values of at least 90.

The plants used in the greenhouse experiments belonged to the followingspecies:

Bayer Code Scientific name Common name ABUTH Abutilon theophrastivelvetleaf AGSST Agrostis stolonifera L. white bent ALOMY Alopecurusmyosuroides blackgrass AMARE Amaranthus retroflexus L. pigweed AVEFAAvena fatua wild-oat CHEAL Chenopodium album fat-hen LOLMU Loliummultiflorum italian ryegrass MATIN Matricaria inodora horse daisy SETFASetaria faberi giant foxtail POLCO Polygonum convolvulus wild buckwheat

TABLE 15 Post-emergence treatment of Abutilon theophrasti (velvetleaf)cpd. no. application rate [kg/ha] damage [%] I.5.4 3.0 85 I.2.1 2.0 95I.1.6 3.0 100 I.1.35 3.0 90 I.2.2 2.0 100 I.2.3 3.0 100 I.2.5 3.0 100I.2.6 3.0 100 I.7.31 3.0 98 I.2.7 3.0 100 I.2.8 3.0 100 I.7.17 3.0 100I.1.61 3.0 100 I.1.62 2.0 100 I.8.2 3.0 100 I.1.66 3.0 100 I.1.67 3.0100 I.1.68 3.0 100 I.1.69 3.0 100 I.1.70 3.0 100 I.1.75 3.0 100 I.8.13.0 100 I.7.41 3.0 100 I.7.38 3.0 100 I.7.13 3.0 100 I.7.10 3.0 100I.7.39 3.0 100 I.2.10 3.0 90 I.4.5 3.0 85 I.2.11 3.0 100 I.4.4 3.0 100I.2.12 3.0 100 I.2.13 2.0 100 I.2.14 3.0 100 I.2.15 3.0 85 I.2.19 3.0100 I.2.16 3.0 85 I.2.17 3.0 100 I.2.18 3.0 100 I.2.20 3.0 100 I.2.213.0 100 I.2.22 3.0 100 I.2.24 3.0 100 I.2.26 3.0 100 I.2.27 3.0 100I.4.25 3.0 100 I.4.27 3.0 100 I.2.30 3.0 100 I.2.31 3.0 100 I.2.37 3.090 I.2.38 3.0 100 I.2.39 3.0 100 I.2.40 3.0 100 I.2.41 3.0 100 I.2.423.0 100 I.2.43 3.0 100 I.2.44 3.0 100

TABLE 16 Post-emergence treatment of Agrostis stolonifera L. (whitebent) cpd. no. application rate [kg/ha] damage [%] I.8.6 2.0 80 I.1.102.0 90 I.1.31 2.0 85 I.1.39 2.0 90 I.1.49 2.0 85

TABLE 17 Post-emergence treatment of Alopecurus myosuroides (blackgrass)cpd. no. application rate [kg/ha] damage [%] I.1.43 1.0 80

TABLE 18 Post-emergence treatment of Amaranthus retroflexus L. (pigweed)cpd. no. aplication rate [kg/ha] damage [%] I.8.4 1.0 100 I.1.64 0.5 100I.1.65 1.0 100 I.7.53 1.0 100 I.2.45 1.0 98 I.1.79 1.0 98 I.1.80 1.0 98I.1.81 1.0 98 I.1.82 1.0 98 I.2.46 1.0 98 I.1.83 1.0 100 I.2.50 1.0 100I.2.51 1.0 100 I.2.52 1.0 100 I.2.53 1.0 100 I.2.54 1.0 100 I.2.55 1.0100 I.2.56 1.0 100 I.2.57 1.0 100 I.2.58 1.0 100 I.4.45 1.0 100 I.4.471.0 95 I.7.55 1.0 100 I.7.56 1.0 80 I.7.57 1.0 80 I.2.61 1.0 100 I.2.621.0 100 I.2.63 1.0 100 I.4.59 1.0 95 I.4.60 0.927 100 I.2.64 1.0 100I.2.65 1.0 100 I.7.59 1.0 100 I.7.60 1.0 100 I.7.61 1.0 100 I.7.62 1.0100 I.2.66 1.0 100 I.7.63 1.0 100 I.7.64 1.0 100 I.7.65 1.0 100 I.7.901.0 100 I.2.71 1.0 100 I.4.63 1.0 100 I.7.68 1.0 100 I.7.69 1.0 100

TABLE 19 Post-emergence treatment of Avena fatua (spring-wild oat) cpd.no. application rate [kg/ha] damage [%] I.1.35 3.0 85 I.1.39 2.0 85I.1.43 1.0 90 I.1.61 3.0 100 I.1.63 3.0 80 I.8.2 3.0 90 I.1.66 3.0 80I.1.67 3.0 95

TABLE 20 Post-emergence treatment of Chenopodium album (fat-hen) cpd.no. application rate [kg/ha] damage [%] I.1.21 1.0 100 I.8.4 1.0 100I.1.65 1.0 100 I.7.53 1.0 90 I.2.45 1.0 98 I.1.79 1.0 85 I.1.80 1.0 98I.1.81 1.0 98 I.1.82 1.0 98 I.2.46 1.0 98 I.1.83 1.0 100 I.2.50 1.0 100I.2.51 1.0 100 I.2.52 1.0 98 I.2.53 1.0 100 I.2.54 1.0 100 I.2.55 1.0100 I.2.56 1.0 100 I.2.57 1.0 100 I.2.58 1.0 100 I.7.55 1.0 100 I.7.561.0 90 I.7.57 1.0 98 I.7.58 1.0 95 I.2.59 1.0 95 I.2.61 1.0 100 I.2.621.0 100 I.2.63 1.0 100 I.4.59 1.0 100 I.4.60 0.927 100 I.7.61 1.0 100I.7.62 1.0 100 I.2.66 1.0 100 I.7.63 1.0 100 I.7.64 1.0 100 I.7.65 1.0100 I.7.90 1.0 100 I.7.66 1.0 100 I.7.67 1.0 100 I.2.69 1.0 95 I.2.711.0 100 I.4.63 1.0 100 I.7.68 1.0 100

TABLE 21 Post-emergence treatment of Lolium multiflorum (italianryegrass) cpd. no. application rate [kg/ha] damage [%] I.1.21 1.0 100

TABLE 22 Post-emergence treatment of Matricaria inodora (horse daisy)cpd. no. application rate [kg/ha] damage [%] I.7.34 2.0 85 I.1.2 2.0 90I.1.10 2.0 85 I.1.24 2.0 100 I.1.31 2.0 95 I.1.49 2.0 98 I.2.4 2.0 98

TABLE 23 Post-emergence treatment of Setaria faberi (giant foxtail) cpd.no. application rate [kg/ha] damage [%] I.7.32 3.0 80 I.8.6 2.0 80 I.2.12.0 100 I.7.4 3.0 80 I.7.7 3.0 85 I.8.5 3.0 80 I.5.8 3.0 85 I.1.6 3.0 95I.2.2 2.0 90 I.2.3 3.0 85 I.2.5 3.0 80 I.2.6 3.0 95 I.8.3 3.0 85 I.2.73.0 100 I.5.13 3.0 95 I.2.8 3.0 80 I.7.17 3.0 90 I.7.9 3.0 85 I.4.2 3.085 I.4.6 3.0 80 I.2.10 3.0 85 I.2.11 3.0 100 I.2.12 3.0 90 I.4.3 3.0 90I.2.13 2.0 95 I.2.14 3.0 90 I.2.15 3.0 100 I.2.19 3.0 85 I.2.16 3.0 100I.2.20 3.0 95 I.4.19 3.0 100 I.2.25 3.0 95 I.7.51 3.0 90

3.0 98

TABLE 24 Post-emergence treatment of Polygonum convolvulus (wildbuckwheat) cpd. no. application rate [kg/ha] damage [%] I.7.58 1.0 90I.2.59 1.0 90 I.2.64 1.0 80 I.2.65 1.0 100 I.7.59 1.0 100 I.7.60 1.0 100I.7.66 1.0 100 I.7.67 1.0 100 I.2.69 1.0 85 I.7.69 1.0 100

1. (canceled)
 2. A compound of formula (I)

wherein R¹ is hydrogen, halogen, C₁-C₆-alkyl, or C₁-C₆-haloalkyl; R² ishydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl, or C₂-C₆-alkynyl;R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₃-C₆-cycloalkenyl,C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl, C₂-C₆-haloalkynyl,C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, C₁-C₆-alkylthio, C₁-C₆-haloalkylthio,amino, C₁-C₆-alkylamino, N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, orphenyl; wherein heterocyclyl is a 5- or 6-membered saturated, partiallyunsaturated or aromatic monocyclic ring, which contains 1, 2, 3, or 4heteroatoms selected from the group consisting of O, N and S as ringmembers; and wherein the heterocyclyl and phenyl moieties of R³ can beunsubstituted or substituted with one or more radicals selected from thegroup consisting of halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl,C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl,C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino,heterocyclyl, and phenyl; X is OR⁴; R⁴ is hydrogen, C₁-C₆-alkyl,C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, orC₂-C₆-alkynyl; or its agriculturally useful salt with the exception ofisoxazolo[5,4-b]pyridine compounds of formula I, wherein R¹ is hydrogen,R² is cyclopropyl, R³ is CH₃, X is OR⁴ and R⁴ is hydrogen, C₁-C₆-alkyl,cyanomethyl, or 2-Cl-2-propen-1-yl; R¹ is hydrogen, R² is cyclopropyl,R³ is CH₂C(CH₃)₃, (CH₂)₂CH₃, CH(CH₃)₂, C(CH₃)₃, cyclopropyl, phenyl,2-F-phenyl, 4-F-phenyl, 4-methylphenyl, 4-methoxyphenyl, 2-furan-yl,1,3,5-trimethyl-1H-pyrazol-4-yl, 1-ethyl-5-methyl-1H-pyrazol-4-yl, X isOR⁴ and R⁴ is hydrogen, methyl or ethyl; R¹ is hydrogen, R² is methyl,R³ is CH₃, CH₂C(CH₃)₃, (CH₂)₂CH₃, CH(CH₃)₂, C(CH₃)₃, cyclopropyl,phenyl, 4-methylphenyl, 4-methoxyphenyl, 3-methoxyphenyl,4-fluorophenyl, 3,4-dichlorophenyl, 2-furan-yl,1,3,5-trimethyl-1H-pyrazol-4-yl, 1-ethyl-5-methyl-1H-pyrazol-4-yl, X isOR⁴ and R⁴ is hydrogen, methyl or ethyl; R¹ is hydrogen, R² is ethyl, R³is CH₃, (CH₂)₂CH₃, CH(CH₃)₂, CH₂C(CH₃)₃, cyclopropyl,1,3,5-trimethyl-1H-pyrazol-4-yl, X is OR⁴ and R⁴ is hydrogen, methyl orethyl; R¹ is hydrogen, R² is i-propyl, R³ is CH₃, CH₂C(CH₃)₃, (CH₂)₂CH₃,CH(CH₃)₂, C(CH₃)₃, cyclopropyl, phenyl, 3-methoxyphenyl, 2-furan-yl; Xis OR⁴ and R⁴ is hydrogen, methyl or ethyl; and R¹ is chlorine, R² ismethyl, cyclopropyl, R³ is methyl, X is OR⁴ and R⁴ is hydrogen ormethyl.
 3. The compound of claim 2, wherein R¹ is hydrogen; R² iscyclopropyl; R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl,C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₃-C₆-cycloalkenyl,C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl, C₂-C₆-haloalkynyl,C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, C₁-C₆-alkylthio, C₁-C₆-haloalkylthio,amino, C₁-C₆-alkylamino, N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, orphenyl; wherein heterocyclyl is a 5- or 6-membered saturated, partiallyunsaturated or aromatic monocyclic ring, which contains 1, 2, 3, or 4heteroatoms selected from the group consisting of O, N and S as ringmembers; and wherein the heterocyclyl and phenyl moieties of R³ can beunsubstituted or substituted with one or more radicals selected from thegroup consisting of halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl,C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl,C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino,heterocyclyl, and phenyl; X is OR⁴; R⁴ is hydrogen, C₁-C₆-alkyl,C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl, C₁-C₆-cyanoalkyl,C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-alkoxy-C₁-C₆-alkoxy-C₁-C₆-alkyl,C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₂-C₆-alkenyloxy-C₁-C₆-alkyl,C₂-C₆-haloalkenyloxy-C₁-C₆-alkyl, C₁-C₆-alkoxycarbonyl-C₁-C₆-alkyl,aminocarbonyl-C₁-C₆-alkyl, C₁-C₆-alkyl-aminocarbonyl-C₁-C₆-alkyl,N,N-di-(C₁-C₆-alkyl)-aminocarbonyl-C₁-C₆-alkyl,[N—(C₃-C₆-cycloalkyl-C₁-C₆-alkyl),N—(C₁-C₆-alkyl)]-aminocarbonyl-C₁-C₆-alkyl,C₁-C₆-alkoxy-aminocarbonyl-C₁-C₆-alkyl, C₂-C₆-alkenyl,C₂-C₆-haloalkenyl, C₂-C₆-alkynyl-C₂-C₆-alkenyl, C₂-C₆-alkynyl,C₂-C₆-haloalkynyl, heterocyclyl, phenyl, heterocyclylcarbonyl,phenylcarbonyl, phenylcarbonyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl, orphenyl-C₁-C₆-alkyl; wherein heterocyclyl is a 5- or 6-memberedsaturated, partially unsaturated or aromatic monocyclic ring, whichcontains 1, 2, 3, or 4 heteroatoms selected from the group consisting ofO, N and S as ring members; and wherein the phenyl and heterocyclylmoieties of R⁴ can be unsubstituted or substituted with one or moreradicals selected from the group consisting of halogen, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,heterocyclyl, and phenyl; or its agriculturally useful salt; with theexception of: Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-fluorophenyl)-methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-[4-(methoxycarbonyl)-3,5-dimethyl-1H-pyrrol-2-yl]-1-methyl-2-oxoethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(3-methyl-2-quinoxalinyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2-methoxy-4-methylphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-[5-(2-furanyl)-3-isoxazolyl]methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(4-ethoxyphenoxy)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-1-(5-phenyl-1,3,4-oxadiazol-2-yl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(5-ethyl-2-thienyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-chloro-2-propen-1-yl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(3,4-dimethoxyphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(4-methoxyphenyl)-1-methyl-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-[2-(3-thienyl)-4-thiazolyl]methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-fluorophenyl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-pyridinylmethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(3-fluoro-4-methoxyphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(4-fluorophenyl)-1-methyl-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-oxo-2-(pentylamino)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(5-bromo-2-methoxyphenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-1-methyl-2-oxo-2-phenylethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-1-methyl-2-[(1-methylethyl)amino]-2-oxoethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methoxyphenyl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(6-chloro-3-pyridinyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-amino-1-methyl-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(2-chloro-6-fluorophenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2-bromophenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(1,1-dimethylethoxy)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-[2,5-dimethyl-1-(3-methylbutyl)-1H-pyrrol-3-yl]-2-oxoethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2,4-dihydroxyphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-[2-(difluoromethoxy)-5-methylphenyl]-2-oxoethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2-methoxyphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(5-methyl-2-thienyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-oxo-2-(2,3,4,5-tetramethylphenyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-[5-(2-thienyl)-1,3,4-oxadiazol-2-yl]methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methylphenyl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(3-fluoro-4-methoxyphenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(7-methyl-4-oxo-4H-pyrido[1,2-a]pyrimidin-2-yl)methylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(4-methoxyphenyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(1-butyl-1H-tetrazol-5-yl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-benzoxazolylmethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-1-methylethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-[(1-methylbutyl)amino]-2-oxoethyl ester;

Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-cyanomethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-[3-(methoxycarbonyl)-2-furanyl]methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(3-methyl-5-isoxazolyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(5-chloro-1,2,3-thiadiazol-4-yl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,1-dimethylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-[(1,5-dimethylhexyl)amino]-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl-,methyl ester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2-oxo-1-imidazolidinyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methoxyphenyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-cyclopropyl-3-methyl-2-methoxy-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-(2,4-dimethoxyphenyl)-2-oxoethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-4-(2-oxo-1-pyrrolidinyl)phenyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-, methylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl-,ethyl ester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(3,5-dimethyl-4-isoxazolyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-[3-(2-thienyl)-1,2,4-oxadiazol-5-yl]methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2,3-dichlorophenyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(8-methylimidazo[1,2-a]pyridin-2-yl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-(2-ethyl-4-thiazolyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl) methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-propyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-propylmethyl ester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-propyl ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-(2-furanyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-furanyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-furanyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl ethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-methyl ethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-methylethyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-cyclopropyl-3-(1-methylethyl)methyl ester; andIsoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-methylethyl)ethyl ester.
 4. The compound of claim 3,wherein R¹ is hydrogen; R² is cyclopropyl; R³ is hydrogen, halogen,hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl,C₃-C₆-cycloalkyl-C₁-C₆-alkyl, C₃-C₆-halocycloalkyl-C₁-C₆-alkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl,C₃-C₆-cycloalkenyl, C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl,heterocyclyl-C₁-C₆-alkyl, C₂-C₆-alkenyl, C₂-C₆-haloalkenyl,C₂-C₆-alkynyl, C₂-C₆-haloalkynyl, C₁-C₆-alkoxy, C₁-C₆-haloalkoxy,C₁-C₆-alkylthio, C₁-C₆-haloalkylthio, amino, C₁-C₆-alkylamino,N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, or phenyl; wherein heterocyclylis a 5- or 6-membered saturated, partially unsaturated or aromaticmonocyclic ring, which contains 1, 2, 3, or 4 heteroatoms selected fromthe group consisting of O, N and S as ring members; and wherein theheterocyclyl and phenyl moieties of R³ can be unsubstituted orsubstituted with one or more radicals selected from the group consistingof halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl, C₁-C₄-haloalkyl,C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl, C₂-C₆-alkenyl,C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy, C₁-C₄-alkoxycarbonyl,C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl, C₁-C₄-alkylsulfonyl, amino,C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino, heterocyclyl, and phenyl; Xis OR⁴; R⁴ is hydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-cyanoalkyl,C₁-C₆-alkoxy-C₁-C₆-alkyl, C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₂-C₆-alkenyl,C₂-C₆-haloalkenyl, or C₂-C₆-alkynyl; or its agriculturally useful salt;with the exception of: Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-fluorophenyl)-methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-2-chloro-2-propen-1-yl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-fluorophenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methoxyphenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methylphenyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-1-methylethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl-cyanomethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,1-dimethylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenylmethyl ester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methoxyphenyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 3,6-dicyclopropyl methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl ethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl)-, methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2,2-dimethylpropyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-propyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-propylmethyl ester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-propyl ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-(2-furanyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-furanyl)methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(2-furanyl)ethyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl ethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-methyl methyl ester;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-methyl ethylester; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-methylethyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-cyclopropyl-3-(1-methylethyl)methyl ester; andIsoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-methylethyl)ethyl ester.
 5. The compound of claim 2,wherein R¹ is hydrogen, halogen, C₁-C₆-alkyl, or C₁-C₆-haloalkyl; R² ishydrogen, C₁-C₆-alkyl, C₁-C₆-haloalkyl, C₁-C₆-hydroxyalkyl,C₃-C₆-cycloalkyl, C₃-C₆-halocycloalkyl, C₂-C₆-alkenyl, or C₂-C₆-alkynyl;R³ is hydrogen, halogen, hydroxy, C₁-C₆-alkyl, C₁-C₆-haloalkyl,C₁-C₆-hydroxyalkyl, C₁-C₆-alkoxy-C₁-C₆-alkyl,C₁-C₆-haloalkoxy-C₁-C₆-alkyl, C₃-C₆-cycloalkyl-C₁-C₆-alkyl,C₃-C₆-halocycloalkyl-C₁-C₆-alkyl, C₃-C₆-cycloalkyl,C₃-C₆-halocycloalkyl, C₁-C₄-alkyl-C₃-C₆-cycloalkyl, C₃-C₆-cycloalkenyl,C₃-C₆-halocycloalkenyl, phenyl-C₁-C₆-alkyl, heterocyclyl-C₁-C₆-alkyl,C₂-C₆-alkenyl, C₂-C₆-haloalkenyl, C₂-C₆-alkynyl, C₂-C₆-haloalkynyl,C₁-C₆-alkoxy, C₁-C₆-haloalkoxy, C₁-C₆-alkylthio, C₁-C₆-haloalkylthio,amino, C₁-C₆-alkylamino, N,N-di-(C₁-C₆)-alkylamino, heterocyclyl, orphenyl; wherein heterocyclyl is a 5- or 6-membered saturated, partiallyunsaturated or aromatic monocyclic ring, which contains 1, 2, 3, or 4heteroatoms selected from the group consisting of O, N and S as ringmembers; and wherein the heterocyclyl and phenyl moieties of R³ can beunsubstituted or substituted with one or more radicals selected from thegroup consisting of halogen, hydroxy, nitro, cyano, C₁-C₄-alkyl,C₁-C₄-haloalkyl, C₁-C₄-alkoxy-C₁-C₄-alkyl, C₃-C₆-cycloalkyl,C₂-C₆-alkenyl, C₂-C₆-alkynyl, C₁-C₄-alkoxy, C₁-C₄-haloalkoxy,C₁-C₄-alkoxycarbonyl, C₁-C₄-alkylthio, C₁-C₄-alkylsulfinyl,C₁-C₄-alkylsulfonyl, amino, C₁-C₄-alkylamino, N,N-di-(C₁-C₄)-alkylamino,heterocyclyl, and phenyl; X is OR⁴; R⁴ is hydrogen; or itsagriculturally useful salt; with the exception of:Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-dicyclopropyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1,1-dimethylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(4-methoxyphenyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-cyclopropyl-3-(2,2-dimethylpropyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-propyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-(2-furanyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-phenyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-cyclopropyl-3-methyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-cyclopropyl-3-(1-methylethyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 3,6-dimethyl; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-propyl; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-(1-methylethyl); Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-(1,1-dimethylethyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-methyl-3-(2,2-dimethylpropyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-cyclopropyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-phenyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-(4-methylphenyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-(3-methoxyphenyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-methyl-3-(4-methoxyphenyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-methyl-3-(4-fluorophenyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-(3,4-dichlorophenyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-methyl-3-(2-furanyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-methyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-methyl-3-(1-ethyl-5-methyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-methyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-propyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-ethyl-3-(1-methylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-ethyl-3-(2,2-dimethylpropyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-ethyl-3-cyclopropyl; Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-ethyl-3-(1,3,5-trimethyl-1H-pyrazol-4-yl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-(1-methylethyl)-3-methyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 6-(1-methylethyl)-3-propyl;Isoxazolo[5,4-b]pyridine-4-carboxylic acid, 3,6-bis(1-methylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-(1-methylethyl)-3-(1,1-dimethylethyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-(1-methylethyl)-3-(2,2-dimethylpropyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-(1-methylethyl)-3-cyclopropyl; Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-(1-methylethyl)-3-phenyl; Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 6-(1-methylethyl)-3-(3-methoxyphenyl);Isoxazolo[5,4-b]pyridine-4-carboxylic acid,6-(1-methylethyl)-3-(2-furanyl); Isoxazolo[5,4-b]pyridine-4-carboxylicacid, 5-chloro-6-cyclopropyl-3-methyl; andIsoxazolo[5,4-b]pyridine-4-carboxylic acid, 5-chloro-3,5-dimethyl. 6.The compound of claim 2, wherein X is OR⁴; R¹ is hydrogen; R² iscyclopropyl; and R³ is 4-difluoromethoxyphenyl; R⁴ is hydrogen.
 7. Acomposition comprising a herbicidally active amount of the compound ofclaim 2 and auxiliaries customary for formulating crop protectionagents.
 8. A composition comprising a herbicidally active amount of thecompound of claim 3 and auxiliaries customary for formulating cropprotection agents.
 9. A composition comprising a herbicidally activeamount of the compound of claim 4 and auxiliaries customary forformulating crop protection agents.
 10. A composition comprising aherbicidally active amount of the compound of claim 5 and auxiliariescustomary for formulating crop protection agents.
 11. A compositioncomprising a herbicidally active amount of the compound of claim 6 andauxiliaries customary for formulating crop protection agents.
 12. Amethod for preparing the composition according to claim 7, whichcomprises mixing a herbicidally active amount of the compound andauxiliaries customary for formulating crop protection agents.
 13. Amethod for preparing the composition according to claim 8, whichcomprises mixing a herbicidally active amount of the compound andauxiliaries customary for formulating crop protection agents.
 14. Amethod for preparing the composition according to claim 9, whichcomprises mixing a herbicidally active amount of the compound andauxiliaries customary for formulating crop protection agents.
 15. Amethod for preparing the composition according to claim 10, whichcomprises mixing a herbicidally active amount of the compound andauxiliaries customary for formulating crop protection agents.
 16. Amethod for preparing the composition according to claim 11, whichcomprises mixing a herbicidally active amount of the compound andauxiliaries customary for formulating crop protection agents.